Listen, Echidna, and listen well. One who stands atop an organization has a duty they must see through, no matter the cost. Leaders are known by many names: Captains. Conquerors. Rulers. We may call ourselves Demon Kings and Queens, but the principles remain the same.

A king must show no hesitation. Why not? If a king shows hesitation, his subjects will also hesitate, worry, and falter.

A king must lead. Why? If a king does not take the first step, his pawns will not follow.

A king must show no weakness. Because a king's weakness is the kingdom's weakness, and the kingdom's weakness is the subjects' weakness.

Never forget. If you are to keep the Demon World alive, always be strong. Always act in a way befitting a sovereign. Always stand proud. Show neither fear, nor hesitation, nor weakness.

"And that's it for my report." I was back in the capital of Svanetia, center of the Demon World. I'd returned from my trip to the outskirts so I could report in to Echidna. "I told Virgo and Canaan to keep making farms around the kingdom. We'll employ local demons to work them and send all the food we grow on them to Lili's logistics people. Pretty good, huh? That's the famine and the unemployment problem cracked in one go."

"Hmm. But no matter what vegetables and grains you grow, they can only be harvested once every few months, right?" Echidna flipped through my report then remarked, "You and Virgo are able to wield time acceleration magic to make crops grow hundreds of times faster, but the local workers will hardly be able to match your efficiency. It doesn't look to me like we're out of the food-shortage fire just yet."

"No need to worry about that," I reassured her. "I went through Shutina to have mid-level royal sorcerers dispatched to every farm we've got. Their acceleration spells aren't quite at our level, but we can harvest each week."

"Impressive!" Echidna looked relieved. "Our food worries are as good as gone, then!"

In all seriousness, her importation of human foods had contributed to our food problems in the first place. I might have stolen a bit too much of her thunder by solving it on my own.

"And you've set things right with Canaan, too!" she added. "Wonderful news!"

"I gave it a shot. Glad you seem happy about it."

"Of course I am happy! Come, now, don't be ridiculous."

On the surface, Echidna looked pleased to have the issues solved. I had been worried her pride might be bruised, but that wasn't the case...apparently.

"Now, Leo, what about the food imports from the human realm? Do we continue them?"

"Yeah, definitely. The demons here just didn't like how they looked. Casting Alteration on their appearance before selling them in the markets should do the trick, don't you think?"

"I can agree to that, indeed I can! As talented as Virgo and Canaan are, making all of those farms will take time. We shall continue the imports, then. I'll tell Shutina."

Echidna stood up and fetched a pen and paper from the shelf nearby, drawing attention to the fact we were meeting in her personal rooms and not her office. I assumed she'd invited me there so we could talk in private, since it was just the two of us.

The room itself was large and well lit, and its luxurious carpet and the weapons of war lining the walls all spoke to it being the dwelling of a warrior queen. It seemed like the decorations were there to project the appearance of royalty and not necessarily a reflection of her taste. People are often mocked for making such decorative choices, but personally, I didn't think it was that bad. Starting with all the tools of your trade laid out before you can go a long way toward changing your attitude.

For instance, I could recall a man who wanted to be a painter. He had talent, sure, but he lacked initiative and found no end of reasons to postpone his ambitions. Change finally came to him when a friend gifted him a set of very expensive paints and brushes. The man hesitated and tried to refuse them, but his friend held firm. That was a real game changer for the man. I cannot put such quality tools to waste, he thought. I cannot let my friend down! And so he painted, day in and day out, until great success found him. And that friend, the neighborhood girl he'd grown up with, married him. Even hundreds of years later, his descendants continued to paint and were popular and well respected throughout the land.

That was just an example, but one that demonstrated the power of starting with the right tools. After spending the time and money to get through the door, one feels like they have to make good on their investment. Echidna had done just that. How she decorated her room, the way she acted, the way she spoke—I had to assume it was all her way of playing the part of queen. And she never dropped her smug, royal attitude for the same reason. If the queen showed a lack of confidence, the people under her would falter. Every boss, leader, and queen had to project confidence at all times.

"Now, Echidna, there's two things I want to discuss before I move on to my next job."

"Hm? What?"

"First, I want to make sure you're fine with what I'm doing next. I want to purify the water."

Echidna paused in the middle of writing her report to Shutina and eyed me suspiciously before replying, "Water? We have countless water sources, and purification facilities to match them. Is that not low among our priorities?"

Her argument was sound. Although the many rivers flowing across the Demon World were heavily contaminated with mana, purification facilities managed to remove most of it. Now, those facilities weren't Mechanical Era treatment plants, or anything like them. Those facilities were watermills that cleaned the water using countless magic stones enchanted with Clearance spells. And they didn't give the people clear water, but they did give them crappy, drinkable water.

"I had Virgo do a deep analysis of the water, and he found something strange...muddying it up at the source."

"Muddying how?"

"That's the best way I can describe it. Everyone thinks heavy magic use causing mana to encroach on nature led to the contamination problem we've got now, but there might be an even more fundamental cause."

"What?! No, that simply cannot be!" Echidna shot up from her chair and shook her head. "Just how much research on our dying world do you think my people have done? The overuse of magic leading to mana contamination is the conclusion we came to after years of study! If that turns out to be mistaken, centuries of understanding will be thrown out the window!"

"Yeah," I agreed. "And I want to find out if Virgo and I are right, or if the scholars are right. That's why I've got to check out the water."

Echidna sat back down with a groan and began to think. I understood how she felt, really. If the theory she'd believed in for so long was wrong, and if an outsider like me popped up and solved her world's greatest problem just like that, well, I'd imagine her pride would suffer a bruise or two. She couldn't just say no, however, since her world's survival was at stake. She was stuck in the valley between pride and pragmatism, a cursed place I knew well from my millennia guarding humanity.

"All right." She finally looked up and nodded. "I understand. After all of the improvements you made to our work environment in the human world, and since you solved our food shortage, I have no doubt of your abilities. If you feel our misfortune is in the water, then go. Investigate as you will."

"Thanks."

"And what is the second matter? Quickly, I am busy."

Dealing with the water had been more of an afterthought. My true concern revolved around what I had to say next: "Echidna. You may not show it, but I think something's troubling you."

"Hm?"

"You want to quit being the Demon Queen, don't you."

"Bite your tongue, you fool!" Echidna howled, and her magic power shot up.

"Whoa."

She'd been blessed by the fire spirit at birth, giving her fire resistance on Edvard's level, as well as the ability to increase the temperature of her surroundings just by focusing her energy. And the room had abruptly grown hot. Too hot. Not physical heat, but spiritual heat. A magical heat. The books and papers around her wouldn't catch fire, but the heat was unbearable. A normal weakling would have been overwhelmed and lying on the floor. Which led me to conclude she was truly, deeply angry. There was no mistaking it.

"Who do you take me for? I am the Demon Queen! Ruler of the Demon World, commander of flames—the Conflagration Empress Echidna herself! I have defeated countless mighty foes and overcome endless trials to become the 105th ruler of the Demon World and save my people!"

"You don't have to tell me twice!" I replied. "Honest!"

"And yet you dare accuse me of wishing to abdicate?"

"Yeowch! T-turn down the heat already!"

"How could I ever even consider such a thing?!"

It was worse than a damn sauna in there! If she had that much pep saved up, I shouldn't have wasted my time worrying about her! Hell, I had to throw up some defensive spells before I literally became toast. Ice Shield? No, Ice Shield and Aqua Veil; doubling up sounded like enough protection!

As soon as I began my spellcasting, Echidna's pulsing energies died down, and the room rapidly began to cool. The fact that I felt chilly after the temperature returned to normal illustrated just how hot it had been, and how angry she was with me.

"Very well," Echidna conceded. "Normally such insolence would earn you a B-Class Demon World torment, whereupon I would blaze you and your bones to ash with a hundred Inferno spells, binding your limbs as a contingency should you somehow regenerate, and slowly burning you starting with your fingers, carbonizing your miserable body, but..."

Holy crap, I didn't need to hear that. And it was just B-Class? How rough did things get in this place?

"Leo."

"Yes?"

"You are an important member of my inner circle, as well as a comrade in the struggle for peace between our worlds. I shall forget about your insolence, so begone."

Two directives—"run" and "fight"—flashed through my mind, and I took a moment to think about them. If I wanted to flee peacefully, then that was definitely my last opportunity to do so. But I decided to stick it out and fight a little longer.

"I can't duck out that easily," I replied.

"Is that right?"

"Come on," I continued, "tell me you haven't been depressed since right before we returned to the Demon World. Like, even today it feels like you haven't been giving it your all. And as your former rival, I'm kind of worried."

"You still push your luck, you fool?!" Echidna warned. "Do you wish to be roasted alive?!"

"Whoa, whoa, whoa!"

"Burnt alive or burnt after death: is this the choice you wish to make?!" Echidna roared, and the room grew blazing hot again.

Feeling that tension and hearing her harsh words was nostalgic in a way. It took me back to when we first crossed swords. But there was no time for memories! Especially when it was that hot! I had to throw up a barrier! "Aqua—"

"Enough," she sighed.

Phew. A second before I could cast Aqua Veil, Echidna's energy shrank back to normal, and the temperature rapidly dropped. My fear subsided along with it. It looked like I wouldn't end up incinerated by an Inferno today.

Her magic may have eased back a little, but not her attitude. Echidna plopped herself down on the sofa at the back of the room without looking at me and didn't say a word. She didn't need to; her expression made it clear that I should shut up and get out. It also told me that if I said anything else to her, she'd roast me for real.

"Echidna," I said anyway.

No response.

"Sorry. That's all I've got to report. I'll go survey that water."

"Off with you, fool of a hero."

I scurried out of Echidna's room and heard the door slam behind me.

"Did I read her wrong?" I asked myself while walking down the long hallway. I began to wonder if I needed to change my perspective.

Echidna had been lacking in energy lately. I first noticed it when we were running low on food back in the human world, right around when Virgo and Canaan's wyvern attack happened. She wasn't normally so ready to accept my ideas and willing to hand over praise. And that'd been happening a lot lately. It wasn't like I'd been slacking off on the job, though. So her appraisals were certainly accurate in that regard. But we were taking about Echidna, the woman who did not yield an inch to protect the world as she fought me at my most serious! Sure, it may sound nice to say she'd calmed down, but it was a little unsettling to see. Add her lack of spirit into the mix, and it seemed likely that she had some sort of trouble on the brain. That had led me to go poking at what I perceived the problem might be.

"But did I read her wrong? Or...?"

Or maybe...

"Damn it all, what am I doing?" After Leo left, I cast three magical locks on my door, withdrew into my bedroom in the back, buried my face in my pillow, and proceeded to kick and flail about out of sheer frustration. "I all but told him he was right! And he could've at least shown a little compassion! Oh, I could strangle him!"

He was exactly on the money. I did want to abdicate the throne. And how could I not? Leo was at fault for being so talented!

I began reflecting on the past. It was years ago. After defeating countless powerful foes, Shutina included, I had finally ascended to my father, Cychreus's throne, but I realized how many problems the world had which I could not solve alone.

To throw oneself at a large problem alone is a fool's errand. Therefore, I created a band of allies I could depend on, starting with Shutina. I tried to place the proper people in the proper roles, like Lili had learned recently. I struggled to overcome my deficiencies, much like Mernes. And, like Edvard, if I caught myself acting arrogant, I immediately nipped it in the bud. Demon Queen Echidna was built up from all of those accumulated efforts. Every single day since my ascension to the throne was filled with effort, struggle, and strife!

However, working with Leo had revealed a painful truth. My abilities couldn't hold a candle to his, on or off the battlefield! He was acting as my subordinate out of respect and as a formality, but I should have been serving under him. Such was the gulf between our abilities. And the sole reason I remained on top was my royal title. Leo simply allowed me to keep up appearances!

Oh, the humiliation! Who could survive such an insult? How could any Demon Queen be so pathetic?

I was tired of holding it all back! I wanted to tell Leo everything! How would he react if he heard what I had to say?

There was certainly nothing new about my desire. I mean, it was only fair! Leo had listened to the Four Great Guardians and given them counsel, so why not me?! All I got was that one conversation over drinks with "Onyx"!

"I understand why not. I am the queen, after all, and a queen stands alone. Logically, it makes perfect sense!"

My father, Cychreus, the previous Demon King, used to tell me that the one at the top must always hold their head up high. If the leader hesitates, so will their servants. A sovereign's worry spreads through their subjects like wildfire, so they must never show weakness.

I did not need to hear that from him, because it all made sense. One who faltered before their servants and acted without confidence had no right to be queen. A ruler needed their subjects to believe that they would show them the way, and that they would not steer them wrong. I swore that to myself. I promised myself I would always strive to be the greatest queen I could be. And I expended the effort to make sure my abilities matched my attitude.

Then along came someone like Leo, who had no problem breaking all the rules. What do you think that does to my confidence?

"Argghhhh!"

Ahhhhh!

"Dammit! What am I supposed to do?!"

Enough! I was closed for business for the day! That was it! No more Demon Queen Echidna! I would go back to being a normal demon!

How was I going to keep this up?!

"He just waltzes in and shows me how much stronger he is than me! He's got me licked in combat, and in experience! And how's my experience supposed to hold a candle to someone who's been alive since the age of Belial?!"

I threw my pillow against the wall, again and again. There was a warp portal beneath it, so the pillow would hit the floor then fall from the ceiling above my bed, back into my hands. Then, of course, I threw it again.

And again, and again.

I'm sorry, Shutina. This pillow was a present from you.

By the tenth toss, my head had begun to cool off and I let out a sigh.

"Stay cool. Keep yourself together. Don't lose it."

I had to calm down. I was the Demon Queen. Conflagration Empress Echidna, 105th ruler of the Demon World. And something was indeed troubling me. Leo's presence made me deeply insecure. I admitted it. Which meant that I needed to speak to someone about it and receive their counsel. Leo himself, if possible, as the Guardians had.

A queen could not show weakness to those under her, but what about Echidna the individual? More acceptable. If I told Leo about all of the worries in my heart, I would feel much better. Speaking with him was my way out. There was only one problem.

"After carrying on like that, will he hear me out if I tell him I don't have the confidence to be the Demon Queen? What about if I ask him to take over?"

Absolutely not! I wouldn't simply be the poor little queen, I'd look like a complete idiot! An absolute buffoon! Damn it all, how I wished for Leo's cleverness! Thinking back, he had always handled things so well, right from the start. Ever since he infiltrated my castle as the Black Knight Onyx, he'd hid his goal and identity so well...

Wait. That was it. "That's it," I repeated, clapping my hands together. That was the answer! It finally came to me! Truly, I was a queen among queens, a genius through and through!

"The solution was so simple all along: a disguise! I need only disguise myself with magic, like Onyx!"

I would put on a disguise and reveal my troubles to Leo! That wouldn't violate my rule that a queen should show no weakness! Ah, how blind I had been! What a flash of brilliance! What a true queen I was!

Bwahahaha!

It was perfect! Perfecto! And there would lay Leo, defeated!

"Just watch, o hero Leo! I, Demon Queen Echidna will seek out your counsel under a perfect disguise!"

Aquarius returned to visit the lake ten days after she'd first found herself in the Demon World. A unit of the DH Series through and through, her pedigree as a superweapon built to protect humanity showed. Her wounds, mortal or otherwise, had healed, and she had returned to daily life.

"Hey there, Undine," she called out and waved. "Are you alone today?"

"Oh, hello, Aquarius!" The girl with her feet in the water looked surprised to see Aquarius and stood up to welcome her as she approached. "Should you really be up and moving around?!"

The girl was clad in an immaculate white robe that complimented her hair, which was a translucent blue and evoked the image of flowing water. She appeared to be a common village girl, but she had an unusual air about her. She was Undine, the great water spirit who brought clean water to the Demon World, guardian of Lake Amia, and Aquarius' savior. And she certainly didn't look like a spirit as she stood there lecturing Aquarius.

"Do you know how injured you were? You really need to rest some more!"

"Don't worry. The village people took wonderful care of me. Saw to it that I'd be right as rain. Besides, I'm built of much stronger stuff than the average human. If I rest any more, I'm afraid it'll do this body more harm than good."

"Well, don't come crying to me if you start to feel bad again later," the girl scolded before letting out a laugh, once again giving no impression that she was a grand spirit.

 Aquarius plopped down next to Undine and dipped her feet in the water, too.

"Say, Undine. There's a few things I'd like to ask, if you didn't mind."

"Go right ahead. I couldn't refuse my dear guest from the human world, so ask anything."

"Anything, you say?! Now I'm tempted to postpone my original questions and ask what your measurements are, instead," Aquarius joked while splashing her bare feet in the lake, but something was tugging at her thoughts. Should she ask? Should she hold off? No, she decided, she had to see it through. In a quiet voice she asked, "Undine. You are a spirit, right?"

"I am. I may look like an elf, but I am a spirit. I wasn't born with a body of flesh and bone."

"I hear spirits come from a third realm called the Spirit World, where neither humans nor demons live. And when we cast spells, we receive mana from the 'Undine' that lives in that realm, but that isn't you, is it. Am I right so far?"

"Yeah, you're right about that," Undine agreed and quietly nodded.

Aquarius had just recited the most basic principles of sorcery. The human and demon worlds, often called the Material Realm, were places where people, demons, birds, and fish alike all possessed physical bodies that allowed them to live. Then there was the Spiritual Realm, where beings existed as thoughts alone, free from the bounds of material existence. Undine came from there.

"To be more precise, I am like a branch of the Undine in the Spirit World, cut from her trunk. There are probably other Undine branches like myself in the human realm, who I'm sure produce pure water over there."

"I'd say you're right about that. Earth's...the human world's clean water is one of its selling points."

Undine must have existed on Earth for thousands of years. You'd be hard pressed to find a corner of the globe that didn't have some kind of legend about a water god. Aquarius figured at least some of those legends came from Undine's miracles, giving rise to religions and being passed on as folklore.

"So spirits gain power from the faith mortals have in them, right?" Aquarius continued. "Is that why they come to the Material Realm and take up residence in the earth, water, wind, and fire, and perform miracles? To build up faith?"

"That's right."

Aquarius had stopped smiling. "My next question, then," she asked in all seriousness, "is why not gather faith in a more efficient manner?" She fixed Undine with a razor-sharp look. "Your magical power is immense. You could probably cross spells with a DH Series unit like myself, or an ordinary demon king. With that kind of power, why not slaughter and pillage, and demand sacrifices? People wouldn't just have faith in you, they'd fear you like a god."

Undine did her best to keep smiling while listening to every word.

"Tell me," Aquarius insisted. "Why not?"

"That's what you wanted to ask me? No wonder you looked so nervous."

"You did save my life. And I figured that question might get me on your bad side."

Aquarius awkwardly scratched her cheek in an effort to hide the other reason for her nervousness. As the twelfth unit in the DH Series, she was built with the sworn duty to protect the world. That "world" had been Earth at first, but after coming to the Demon World and experiencing it, her definition expanded. Whether human or demon, both worlds had their peaceful towns and villages, and their mortals going about their daily lives. Aquarius was convinced that washing up on the shores of Lake Amia had been God's way of telling her to protect the peace in the Demon World, too.

That made Undine stand out in her mind. If the girl sitting beside her was in truth an evil spirit, then one day, they would have to fight. Undine was a good friend, but if their destiny was battle, then Aquarius wanted to part ways with her sooner than later, preferably before she got attached. Hence the reason for her timing, she feared if she waited to ask Undine later, it would be too late.

"I really don't want you think less of me," Undine began to reply while awkwardly stroking her blue hair, "but I should come clean." She was looking down at the ground with a painful grimace on her face. "Everything you just said, I used to do. Ages ago."

Aquarius was stunned.

"What could be faster than a show of strength?" Undine continued. "I took the form of Leviathan, a water dragon haunting Lake Amia, and I caused floods and polluted the water unless the villagers gave me sacrifices."

"I can...hardly believe that..." Aquarius murmured. She didn't think any less of Undine; she simply could not believe what she was hearing. The Undine sitting before her looked like a village girl you might find in any country hamlet. In no world could she see that girl throwing her weight around, bringing disaster, and demanding sacrifices while controlling people with fear. Leviathan, it seemed, had been a completely different Undine. Less of a spirit, one could say, and more of a living disaster. That was the reason for her disbelief.

Undine sensed she wasn't being judged and said a quiet word of thanks before continuing her story.

"We branches come from the Spirit World, which is a completely different place compared to the human and demon realms, as you said. The beings there are radically different. We cannot...understand the minds of mortals."

"The minds of mortals?" Aquarius repeated.

"Right. Let me put it another way. Do you know what a lizard or a turtle is thinking as they go through life? That's how I was. I had no idea how the denizens of the Demon World thought, and I did not care. I only had my purpose, which was to show the power of Undine and gain converts."

"And so you took the quickest path?" Aquarius asked. "Flooding the fields, polluting the water, and demanding sacrifices?"

She did not know how many years had passed since Leviathan's reign of terror, but fear, once implanted, was slow to fade. And yet, the people from the water village nearby showed no fear or hatred towards the spirit. So perhaps it had been hundreds of years ago, or even thousands.

Still, the regret ate Undine up as if it were yesterday. And her sad, unwavering gaze told the tale.

Aquarius stared right back into those sad eyes and said, "Then, I have another question. How did you become so like a human?"

"You may have been an evil god in the past," Aquarius said, "but now you live among mortals as a humble village girl. How? You were a raging spirit with no concept of what it means to be human. What changed?"

Evil god and raging spirit were not the most appropriate words to lay on the person who had saved her, but Aquarius used them with intent. To hide behind euphemisms would only insult her benefactor.

"First, I was defeated by the Demon Queen when I was Leviathan," Undine explained. "And how could I not draw her ire, after all the damage I had done?"

"That's a surprise. I didn't think demon monarchs cared so much for their subjects. What happened next?"

"The Demon Queen at the time believed I acted as I had because spirits did not understand the minds of mortals. So, Aquarius, if that lack of understanding is what led to my tyranny as Leviathan, how do you think she solved it?"

It was a simple question, and Aquarius felt she'd already been given the answer. After thinking about it a moment she followed her intuition and replied, "By teaching you the mortal mind?"

"Exactly." Undine placed her index finger on the tip of Aquarius's nose. "A rare few are born with the powerful blessing of the spirits, and their physical bodies are, in many ways, more in tune with us. You're like that too, aren't you?"

"Mhm. I'm a bioweapon made to specialize in the ice magic arts. I've been strongly blessed by the dark spirit Shade and the water spirit Undine."

"Well, people like that have the potential to reverse the relationship. They can grant their power to spirits."

Undine slowly lifted her right hand and held it out toward Aquarius and encouraged her to do the same. Aquarius responded by placing her hand on top. At first, there was no reaction. Then suddenly a bright light as deep blue as the sea filled the space between them.

What happened next came as a shock to Aquarius. Her mind was suddenly filled with Undine's thoughts and feelings. In fact, their linked palms allowed her to experience all of Undine's memories and emotions, even as Leviathan. She saw her battle against the Demon Queen, then felt her loss at her hands, and finally...

"Ah. So it went." Aquarius shook her head then gently massaged her brow while attempting to organize the maelstrom in her mind. "The Demon Queen at the time, Crocell, used a mortal blessed by Undine as a priestess, and she bestowed her mind upon you, much like you've just done to me."

"Right. And she continued to tune my mind until it gradually began to mirror that of a mortal. That is how I came to be."

"What happens if someone slacks off on the tuning?"

"I think my mortal mind will grow dull, and I'll revert to the way I was before."

"So you'll go back to being a destructive god in an effort to gather faithful followers."

Undine's skirt fluttered around her as she abruptly stood up. She then stretched her arms wide, as if to bear all of Lake Amia. "I love this world," she said. "I really do. It may be a little dark and gloomy, and the land a little barren, and it has a population that does nothing but fight, not to mention how all the recent Demon Kings and Queens are fools who want nothing more than to invade the human realm..."

"You sure are tearing into the place, huh?" Aquarius giggled.

Undine giggled too, then continued, "But this is the world that made me a mortal person, and I want to keep on living here. And I want to keep bringing it pure water, as the water spirit Undine."

"Yeah?" Aquarius let out a quiet sigh that was filled with both relief and regret. "Forgive me," she then replied. "It seems my worries could not have been more wrong."

"Worries? What were you worried about?"

"Never mind. It's nothing."

The thought that the girl standing before her might be evil and that Aquarius might have to defeat her in the future was ridiculous. Though embarrassed by her foolishness, she took Undine's hand and knelt down before her. It was both an apology and an expression of deep friendship.

"Then I shall become your knight, Undine."

"My knight?"

"I may not look it, but I am immortal. If you wish to keep living in this world as a spirit, then I will be your knight and companion. I've been blessed by water since birth, so I think we'll get along fine. What do you think?"

Undine stared back in surprise. Aquarius did, indeed, strike her as different from the others. She had greater power than a Demon King, but her heart was pure. She almost seemed to be more spirit than mortal. They would likely get along quite well. More importantly, it was a first for Undine. No one had ever come to her, an immortal, and said they would be her companion for life.

Undine shyly smiled, then barely managed to choke out a thank you as her emotions came welling up.

"So Lake Amia is just ahead, right?"

"Yeah, we'll see it right after we cross over this mountain. Let's get going."

The boy beside me nodded silently and adjusted his verdant hood. His name was Mernes, and he was leader of the Assassins' Guild and one of the Four Great Guardians. People called him the Unseen Blade, and not for nothing. With world-class assassination skills at the mere age of sixteen, he was the dark army's fastest sword.

Mernes was accompanying me on a journey through a mountain range far removed from the capital, on a mission to survey the land's water. Obviously, water was essential to civilized life. Water to drink, water for bathroom business, water for irrigation—things would fall apart without those, so we needed to solve the water problem as soon as possible.

Lake Amia, quietly hidden away in those mountains, had been a massive water source for the capital and its surroundings. Had been. Extensive mana contamination rendered it unusable several hundred years ago, and it was since abandoned.

"Why didn't they check this place out right away?" Mernes wondered. "If the water's polluted, first thing you should do is check the water sources around the land. Is the Demon World full of idiots or something?"

Most of the water in the Demon World was polluted. The seas, the rivers, the ponds, the lakes, everything. The scholars of the land believed that the overuse of magic leading to a buildup of mana was the main cause of the contamination, but that was no reason to slack off on surveying the water. Mernes' bafflement was well justified.

"Oh, they did," I explained. "Demon Kings throughout history have sent survey teams to Lake Amia time and time again, but they've all ended in failure. The lake's got some insane guardian. They call themselves the 'Demon King Slayer.'"

Mernes gave me an even more baffled look that said I couldn't be serious.

I wanted him to cut me some slack, because I thought it was ridiculous, too.

"When you say insane," he asked, "do you mean insanely strong? Or just insane?"

"Probably both, really. There's been a total of fifteen survey teams sent over the past few hundred years, but the Demon King Slayer fended them all off. Hell, some angry Demon Kings visited the lake for revenge themselves and got slain."

"Hence the name Demon King Slayer, then."

"Yep. Pretty wild, huh?"

No one knew who this "Demon King Slayer" guardian of the lake really was, but battles with them had revealed three things. One: negotiation was impossible. If they see you, you're fighting. Two: they protected Lake Amia. As long as you stayed away from the lake, you had nothing to fear. Three: they were strong. Incredibly strong. That was why I brought Mernes with me. As an assassin, water wasn't his specialty, but he sure as hell specialized in ambushes.

Fight fire with fire. No matter what kind of ambush the Demon King Slayer came at us with, he would sense it. And if we could overcome the ambush, there was no opponent Mernes and I couldn't defeat together.

"That the place?"

"Mmm...yeah, that's it. Whoa, it's murky as hell."

After crossing over a mountain a bit too tall to call a hill, we could see what looked like a lake beyond the trees. Its waters looked black as tar, and I could tell even from a distance how radically filthy it was. Yet, that was Lake Amia, the base of the Demon King Slayer.

Moving forward meant crossing into their territory, which could hold any number of hidden traps.

"How'll we do this, Leo?"

"Let's just approach it normally, for now. The last survey team visited before Echidna took the throne, so we don't even know if this guardian's still al—"

"Get down, you moron!" Mernes cried out with surprising urgency while grabbing me and pulling me to the ground.

"Whoa!"

Immediately afterward, a massive spear of ice flew past where I'd been standing.

I looked up, stunned. An ice spear as thick as a log was protruding from the tree behind me. If it had hit me, I probably would've been in serious shape.

Mernes shot me a questioning look, then said accusingly, "You been slacking, Leo?"

"No, seriously, I didn't sense that one at all! And don't tell me you've forgotten how I can dodge even your ambushes if I'm really focusing."

"Point taken. So that must mean..."

"Yeah," I finished his sentence, "this person's the real deal. Keep your guard up."

Not a moment after I said it, the weather began changing before our eyes, and the temperature plunged. That was one more thing we knew about the Demon King Slayer: they used ice magic and were incredibly good at it.

Ice magic is cast by mixing the powers of the water spirit Undine with the dark spirit Shade. The Demon World was stuck in a state of perpetual twilight, which gave Shade strength, and Undine was stronger when next to a massive lake like Amia. Together, that had the potential to make any ice magic exponentially stronger.

Crunch, crunch, crunch...

We could hear the ground crunching beneath someone's feet as they slowly walked toward us.

"Sleet Valve, it's called. I invented the spell myself."

The voice came from a sorcerer in a white mask. They wore an ultramarine robe that was embroidered with the mark of Undine and had a hood as deeply concealing as Mernes'. The individual was shorter than me, but a touch taller than my companion; not a large, imposing figure in the slightest. And they possessed an androgynous voice, but I imagined it belonged to a she.

Judging from the magical power radiating from her being and that near-fatal ambush, the person before us had to be the Demon King Slayer. Rather than pressing the attack, she stood there looking relaxed and unguarded, and I heard no sign of tension in her voice as she continued her explanation.

"I take tiny particles, invisible to the naked eye and packed with Sylph's power, and wrap my target in them, isolating them from all sound and tactile vibrations. Near this lake, no one can avoid my ambushes. Looks like your friend saved you."

The Demon King Slayer pointed at me, then at Mernes. She was right. Mernes was born with a particularly strong blessing from Sylph, and I figured that was why he could see through the wind spirit's cloaking magic.

Everyone and everything that lived in the Demon World had some form of blessing from the spirits. Demon Queen Echidna and Dragon General Edvard had the fire spirit's blessing, Mernes had the wind spirit's. Lili couldn't use magic, but she had powerful earth blessings and claimed she always felt incredibly strong after sleeping outside. The spirits were powerful beings, and their blessings were varied.

"Do we really have to listen to this?" Mernes complained. "She's obviously against us."

He then drew the daggers from his belt and prepared for a fight.

I understood where he was coming from. There were generally two types of people who proudly explained their powers: the plotting type and the really stupid type. There was no way the Demon King Slayer was the latter, so his desire to take her out before we fell into her trap made perfect sense.

"She's plotting something," he voiced my thoughts. "There's no way she isn't. Let's take her out now and save ourselves the trouble."

"Whoa, whoa, hold up!" I quickly replied. "We're not here to fight, we're just here to survey the water! There's nothing better than solving things peacefully! Don't you agree...? Uh...?"

Our opponent quietly observed us and said nothing.

"Uh...Demon King Slayer?" I continued. "That's what you go by, right?"

"It is," she finally responded.

That was a very positive sign. Perhaps she wasn't the uncompromising monster the stories made her out to be.

"I am the Demon King Slayer. Destroyer of fools who trespass on Lake Amia, and guardian of Undine."

"Knew it. So the water spirit Undine is sleeping in this lake, right?"

Lake Amia wasn't just any lake. It was where water spirit Undine, one of the great spirits who ruled over the four elements, lived. And it was only recently that the academic world came to understand that.

Undine was responsible for producing clean water. It didn't make sense for the spirit's lair to be the most polluted body of water in the Demon World, regardless of how much mana contamination there was. Which presented only one possible answer: something happened to Undine.

Something corrupted Undine's power, and that ended up corrupting the Demon World's environment, bringing us to the sorry state we were currently in. If Undine's power was messed up, no wonder water all over the world was polluted.

I had read through all of the available papers and information sources, fishing through past records as thoroughly as I could. In my research, I discovered that hundreds of years ago a Demon King named Ronove had driven Undine into a frenzy on purpose, then thrown her into his enemy's territory.

The Demon World was a land of war. Villages, towns, lords—all of them constantly fought over resources. War came as easily as breathing to the world's denizens, and it was only a matter of time before someone like Ronove had the bright idea of using even the spirits of nature as weapons. Undine became a victim in one of history's countless wars after being forced into a frenzy and manipulated against her will.

Not wanting word of his dark deeds to see the twilight of day, Ronove cleverly hid the truth. The sheer number of records he rewrote and cooked up meant that the strangeness of Lake Amia escaped most scholars. And with the terror of the Demon King Slayer present, the establishment had a perfect reason to ignore the lake.

That said, Mernes and I were on a mission to investigate the waters of the lake and find out what happened to Undine. The Demon King Slayer was a bonus. And that bonus addressed us with a bone-chilling voice.

"State your name and business. What are you doing here?"

"I'm Leo, and the walking threat beside me is Mernes. We..." I hesitated.

What's the play here?

I still didn't know why our opponent was acting the part of Demon King Slayer. She was clearly hostile to the throne and its servants, though. Hiding the fact that we served Echidna was probably the best play.

"We live downstream from Lake Amia. The water pollution's gotten worse, so people have been getting sick. I did some research and found out that Undine's supposed to live here. Do you think you could let us poke around a little?"

"Absolutely not. I can't let anyone sully the lake."

"We won't sully it or anything. We just want to survey it a tiny bit."

"Out of the question," the Slayer refused. "Begone with you."

She wasn't giving an inch. Although she wasn't threatening us at the moment, I assumed she would attack if we tried to ignore her. Mernes let out an impatient sigh and took a step forward.

"Look, we're here on business, okay? We've got authorization from Demon Queen Echidna."

You fool!

The moment the words "Demon Queen" popped up, a wave of anger burst from the Slayer.

"Demon Queen, you say?"

"You can be the Demon King (or Demon Queen) Slayer all you want," I quickly spoke up in our defense, "but the current regime's really different. She's all about peace and improving the world. I don't know how dumb the Demon Kings in the past were, but violently defending your turf like this just puts you on their level. Calm down."

"......"

Following a long moment of silence, the Slayer cried out, "So you do serve the Demon Queen! Die!"

Immense magical power pulsing from her told me that persuasion was impossible, but Mernes muttered, "You've gotta be kidding me. You just want to fight?"

"You've got to be kidding me, Mernes!" I yelled at him. "She's the Demon King Slayer! Did you really think it was a good idea to bring up Echidna?!"

Hearing about the throne was all it took to anger her. It was like she had an allergy or something. Did a Demon King kill her lover? Burn down her village? Regardless, I had to do something. I wanted things to end peacefully...but before I could put my thoughts in order, Mernes had disappeared.

"Hey! Mernes, hold up!"

"No point in wasting time talking," he replied. "I'm killing her."

He had cast two of his signature spells, Shadowless and Blurry Fire. By jumping off of invisible platforms he'd conjured in the air, he could attack his foe from any direction. He got behind her before I could stop him and thrust his dagger towards her back.

"Wait, Mernes! Get away from her!"

By the time he heard my voice, it was too late. The moment his blade came in contact with the Slayer, it froze. The blade, his hand, and his arm were all instantly covered in a thick sheet of ice.

"How careless, boy," the Slayer scolded him. "Don't you know what happens when you approach a sorcerer of ice?"

She didn't even give Mernes a chance to reply.

"Luminous Coffin!"

In the blink of an eye, he was encased in ice. He wasn't dead, most likely, and he should be able to work his way out eventually, but he was still out of the fight! At least he'd managed to demonstrate her trump card beforehand. She had an automatic freezing counterattack spell!

The Demon King Slayer was to be feared. She'd spotted Mernes' weapons and grasped his fighting style in a matter of seconds. No matter how fast a melee fighter was, they still had to close the distance at the moment of attack. And it took nerves of steel to wait for that moment to make your counterattack!

"One down," the Slayer observed after appearing to regain her composure. "Now, it's a duel."

Then again, her previous rage had likely been an act. In fact, coming out into the open and taking the time to converse with us was probably done to invite Mernes' attack. Then she could freeze him with her counterattack spell and isolate me. I had to admit she was a formidable opponent.

The Slayer and I stood several paces apart, glaring at one another. We were at an impasse.

"Well?" she said, breaking the silence. "Are you going to fight me?"

"I'm not. I'd really rather we talk this through."

"You've even lost the drive to avenge your comrades? My, how cowardly you've become."

"What the hell?" I voiced my surprise. "It sounds like you knew me back when I wasn't so 'cowardly.'"

"..."

A hypothesis began kicking around in my head. Why did she use her ambush to single me out? I was a skinny man, and Mernes was a short boy. Ignoring the fact that neither of us appeared to be strong, if you had to pick one of us to fight first, it should be Mernes.

I looked like a complete scrub. I wore basic-as-hell clothes and had nothing but a longsword hanging from my belt. Your average local village militiaman was more kitted out than me. Mernes, on the other hand, was dressed like a murdering professional. From the green hood pulled low over his eyes to the loose coat that camouflaged his reach, he looked the part. Someone as seasoned as the Slayer would, and should, go for Mernes.

And yet, she picked me as her first target. I decided to try a bit of a gamble.

"Now then, what will it be?" she demanded. "Will you avenge your comrade? Or will you run back to the Demon Queen, begging for reinforcements?"

"I will do neither."

"What?"

"I said I will do neither. Miss Slayer, we have no need to engage in a pointless altercation."

The Slayer gave me a bewildered look. I had suddenly begun talking like I did way back in 2060, when I fought off demons in Tokyo and other hotspots around the globe. If she was who I thought she was, that would be the best way to get a reaction from her.

"We are here to save the Demon World," I continued. "We've recently discovered that Lake Amia and Undine quite likely have something to do with the water pollution. However, it was difficult to spot with all of Demon King Ronove's record tampering."

"Are you here to kill Undine?"

"That would probably be considered the most efficient solution."

Truthfully, killing Undine may have been the quickest way to restore the Demon World's water supply. The spirits we knew in our material world were fragments of much greater powers from the spiritual world. They represented mere branches, or terminals of those powers. As long as the spirit Undine remained alive in the Spirit World, another Undine would replace the one in the Demon World, as many times as it took.

Something was happening to the current Undine. If that was what was polluting the water, then killing her off would be the surefire way to make it clean again.

"However, the Demon Queen I serve, Echidna, does not like such violent methods."

"A Demon Queen, against violence?" The Slayer sounded incredulous.

"A Demon Queen against violence.  Or, to be more precise, she wishes to avoid sacrificing one for the good of another. If there is a way to save this world without slaying Undine, Demon Queen Echidna would choose it. No matter how difficult it might be."

"You're a human, from the looks of you. I heard that Echidna invaded the human world. Don't you hold that against her, putting your world in danger?"

"Oh, no, I'm grateful to her. I put the world in danger, and it was she who stopped me. She saved my life, and even gave up the Wisdom Stone she so craved in the process."

"...Did she, now?"

I spoke only the truth. Echidna had invaded the human world, and I defeated her. But when I lost my senses and put the world in danger, it was she who stopped me. The only reason I was still alive was because she came to my rescue.

"That is the kind of ruler she is," I explained. "She's completely different from the Demon Kings of the past. That, I can guarantee."

"And what worth do your words have?"

"I may not look it, but I have lived three thousand years and fought Demon Kings throughout history. I have confidence in my appraisals."

There was a long silence before the Slayer finally responded, "I see. So you've protected the human realm for...quite some time..." Then her voice trailed off into another long silence. She seemed to be giving quite a lot of thought to what she herself had just said.

"Your name?"

"Leo. Leo Demonhart. People call me a hero."

It was a strange conversation. I felt like I was introducing myself, selling Echidna's goodness...and reminiscing about the past, all at once. "Demon King" and "Demon Queen" came up plenty of times, but the Slayer simply listened and even nodded on occasion.

When she spoke up at the end, her voice had lost most of its edge.

"There is one last thing I will ask you, Leo. Tell me, what is it you're after?"

"I want to survey the water. Although I can't imagine you'll be satisfied with that answer."

"Indeed. That wasn't what I meant."

She must have been thinking on a broader scale. I contemplated her question a moment then opted for the simplest answer.

"World peace."

"...Excuse me?"

"The Demon Queen wishes to save the Demon World, while I want to protect the human world and pay her back for saving me. That leaves me with one option. I have to save this ruined land, establish peace between our realms, and create a world where no one has to fight."

"So cleaning up the water is part of your pursuit of said world peace, then. I'm sure you realize there has never been a single moment in history when the human and demon worlds were at peace. Not even the previous Demon King Cychreus could achieve such a feat."

"If it has never happened before, then we will simply need to be the first to accomplish it. History's biggest paradigm shifts are always made by those brave enough to risk failure and step into the unknown wilds."

"And you think you'll be the ones to do that?"

"I do, as long as the Demon Queen and I work together."

The Slayer hesitated before replying, "Is that so?" Then a long paused followed, after which I heard her mumble to herself, "I see."

 By that time, the hostility in her voice had long since vanished, and I could almost say she was starting to warm up to me.

"All right," she replied. "Now there's absolutely no question in my mind what kind of person you are now."

"Thank you very much for listening."

The Slayer laughed. "You can stop speaking like that," she said while pulling off her mask. "And I'm sorry I made you go to all that trouble." She then slipped off her hood to reveal short, golden blonde hair.

That androgynous face and voice. Her use of ice magic and a subzero automatic counterattack spell... The Demon King Slayer turned out to be exactly who I expected. My speech reflexively slipped back to the year 2060, even though I was done acting.

"It has been too long. Three thousand years too long, in fact. DH-12 Aquarius."

"It sure has, Leo. And you've changed quite a bit."

Standing before me was a fellow DH Series unit who I'd thought had died in the battle against Demon King Belial three thousand years ago: the British Ice Sorceress, DH-12 Aquarius.

"So, could you explain something, Aquarius?" I asked. "What are you doing here? Why are you Undine's guardian?"

"I'll explain from the beginning. Sorry I can't provide more hospitable accommodations, though."

"If you're going to apologize for anything, apologize for freezing me," Mernes complained.

"Hahaha, well, you did strike first, didn't you? I was simply acting in self-defense."

Following our encounter, Aquarius and I thawed Mernes, and all three of us gathered around a campfire in a small mountaintop clearing overlooking Lake Amia so we could rest and chat.

Mernes was pretty surprised to learn that the Demon King Slayer was a DH Series unit, but seemed more concerned with the fact that she'd frozen him. He'd been hostile towards her the whole time.

"Putting that self-defense matter aside," Aquarius continued, "let me tell you about what I've been doing since I came to the Demon World. Leo, you remember the final battle against Demon King Belial, right?"

"How could I forget it? You were attacking the castle's east tower, right? I remember you taking on General...Astarot, was it?"

That was three thousand years ago, but I remembered it like it was yesterday. The year was 2061, and the entire world had come together for the singular purpose of defeating Demon King Belial. We DH Series units led the charge into the Himalayas, where Belial's dark castle lay.

Belial was an Annihilationist. He believed that both human and demon alike should perish, along with their realms. Only through that destruction would both peoples be free from pain, fear, and despair. In essence, Belial's invasion was the worst type of group suicide, the type that involved countless others. In that case, two worlds.

As one might expect, the generals under him were not your average villains. To them, win or lose, destruction was all that awaited, so they came at us with no consideration for their own lives. Aquarius was certainly prepared for death when she went to face General Astarot.

"I'd managed to defeat Astarot," she kept explaining, "but I didn't have the energy to escape the castle and was caught in the collapse. But luckily, I'd fallen into the Great Spiritual Hole and its passage to the Demon World. So I ended up here, on the brink of death."

"You actually survived all that?!"

"Well, if nothing else had happened, I wouldn't have. I managed to drag myself to Lake Amia, but couldn't lift a finger after that. The people of the water village and the spirit of the lake they worship, Undine, saved me."

Aquarius gave Lake Amia a nostalgic look. Whether she was remembering how beautiful the lake was back then or how kind the people had been, I could not say, but she was surely recalling what had been lost.

"They were good people, and Undine and I became good friends. Bandits attacked from time to time, but I made short work of them."

"Heh, I bet."

The Demon World was filled with wars, but most of them were minor squabbles between lower level demons. It would take one as powerful as Belial to be a match for a DH unit like Aquarius.

From her demeanor, I could imagine that she was a dear friend to both Undine of the lake and the villagers that worshiped the spirit. It was also apparent that she was as much of a guardian of the lake as Undine was.

"But you weren't able to protect Undine when it counted, huh." Mernes, who had been silently putting twigs into the fire, spoke up. "Demon King Ronove turned Undine into a weapon hundreds of years ago, right? Aren't you supposed to be the Demon King Slayer? Couldn't you beat him?"

"I couldn't, I'm afraid. He didn't have all that much combat ability, but he made it all the way to the dark throne with the help of one special skill. Tell me, Mernes, do you know what that was?"

"I hear it was perception blocking."

"That's right."

Perception blocking, or area hypnosis, was a type of illusion magic used to corrupt the targets' perception, forcing them to fight each other. If the spell got through one's resistances, it had immense effects. Getting pricked by a needle could feel as painful as being shot with a gun, and a tiny rabbit could look like a fire-breathing dragon.

It wasn't just illusions, either. Ronove was talented in bending and rewriting all sorts of realities. He didn't just have magical power, either. He also possessed keen negotiating skills and considerable wealth. All of those came together to help him conceal the truth of Undine's frenzy in Lake Amia right up until the present.

"He lured me to the capital, saying he wanted to build a fortress near the lake." Frustration crept into Aquarius's voice as she continued. "And he sweetened the deal by offering rewards to the villagers if we complied. When I arrived, however, he slowly began to work his illusions on me, bringing me deeper into his mire. By the time I realized I'd been had, it was too late."

That was the problem with running a one-man operation. When one person kept the whole ship afloat, there was no one to take over when they were gone. If I was trying to take Lake Amia, I would have sent a spy to the village, then lured Aquarius out after discovering she was the backbone of their defenses. Ronove had certainly done just that.

"So Ronove attacked the lake while you were out, drove Undine into a frenzy, then unleashed her into his enemy's territory, I presume?"

"Indeed. When I got back, the people of the water village who resisted had been killed, and Undine was gone. I managed to find her again later, but she wasn't even a shadow of her former self. And I had no idea how to calm her down, either."

"So that's why you sealed her deep inside the lake, then."

We all paused to look down at that tar-black body of water. Our clearing had a good view, and it was then I noticed the surface was still. Lake Amia was a frozen lake. Aquarius had done it, of course. To stop Undine's frenzy, she must have frozen both her and the lake to seal her away.

"Unfortunately, that action was flawed," Aquarius explained. "Undine was just too powerful in her madness. If I left the lake, the seal would soon break, so I could not go in search of help."

"Why'd you become the Demon King Slayer, then?" Mernes sharply interjected. "Even if the Demon Kings of the past were idiots, they would have helped if you told them what was going on, right? Isn't beating back all of the throne's survey teams to Lake Amia the exact opposite of helping Undine?"

"That was Ronove's doing, too. After learning that I'd sealed Undine in the lake, he cast a curse on the entire Demon World. That curse gave people the illusion that anyone dear to Undine was a monstrous fiend. I was unable to talk to anyone until it recently wore off after five hundred years."

"Seriously? He cast a spell of that level and kept it going for five hundred years?!"

"You have to remember, he was a Demon King. Although it apparently took a lot of his lifespan. I guess he really wanted to isolate me and keep me quiet, since I was the only one who knew the truth."

"Was he an Annihilationist, or something? If Undine remains in her frenzy, it's only a matter of time before the Demon World is toast."

"Perhaps he was. There were rumors he belonged to a strange group which sought salvation through the death of both human and demon realms."

"Same as Belial, huh?" I replied with a groan and Mernes nodded. "I guess they wanted to carry the torch the 'great Belial' left behind."

The Demon Kings would consider Aquarius a foe. She was forced to stay by the lake while Undine's frenzy caused it to grow more polluted. And when the Demon Kings kept sending survey teams to investigate, they saw Aquarius as a fierce beast and attacked her, meaning she had to fight back.

She was stuck. That was the long and short of it. With that kind of past, of course she'd become the Demon King Slayer. Ronove must have assumed a future Demon King would eventually slay her, even if he didn't. Which meant when we popped up saying we came to do a survey at the behest of the Demon Queen and we were not her enemies, it did little to calm her battle readiness.

"I was surprised to see you, Leo, what with you being built around Hyper Self-development."

"Heh. I suppose you weren't too pleased to have me as a possible enemy after three thousand years of level ups, huh? Conversation was probably the last thing on your mind."

"I wanted to scream, I kid you not. That's why I tried to kill you off in the first strike."

"It failed though, thanks to me," Mernes gloated with a snort. "Heh, don't even try an ambush when I'm around." He was a little bit too competitive, if you asked me.

"Right you are!" Aquarius replied, dodging his sharp remark like a willow bending nimbly in a gale. "I lost, completely and utterly. You really are something, Mernes!" It seemed like she was growing used to his personality. "I'm glad the ambush failed, though. That let me see that you haven't changed at all, Leo, and that Demon Queen Echidna is completely different from her predecessors. Quite the results, I'd say."

"So the misunderstanding's been cleared up, and everyone's happy. Great. So..."

"Yeah?"

"Now what?"

"Good question." Aquarius folded her arms and pretended to give it some thought.

There was nothing for her to think about, of course. If we wanted to purify the Demon World's water supply, then killing Undine, the source of the contamination, was the quickest way. If Undine fell, then a new branch would eventually come from the Spirit World. It wasn't the most encouraging way to put it, but Undine had no shortage of replacements. There was no reason not to remove the source of the corruption.

However, the new branch wouldn't have the old one's personality or memories. That was the source of Aquarius's hesitation. The Undine she'd spent countless years with was there, in the lake, and nowhere else. If she killed her, Aquarius would lose her dearest friend for all eternity.

"To tell the truth, I count killing Undine as one of my choices," she said quietly, as if she'd read my thoughts. "We can't just leave her here in this frenzy, after all. Even if you had come here to fight, I was hoping to persuade you to fight her with me."

"You'd ask us to help you defeat Undine to purify the land's water, huh?"

"Yeah. She's a little too strong for me to beat on my own."

"She's really that tough?"

"For one thing, she has the same elemental affinity for water as I do. But more importantly, her frenzy has given her quite a bit more power. I figure it would take three DH Series units to defeat her. With just you and I, and your Demon Queen and her generals, we probably—"

"Wait, there are three DH units," Mernes interrupted her.

"Huh?" Aquarius gave Mernes a startled look.

"This guy named Virgo got beat down by Leo and joined the army a while ago. Leo can tell you more about him. Anyway, you, Leo, and Virgo make three in total."

"Virgo?!" Aquarius, who was always very composed, was unable to hide her surprise as she turned to look at me. "Y-you can't be serious! He's alive, too?!"

"Mernes is telling the truth. Virgo's situation is a little complicated, and I'll explain later...but he's mostly fine. His personality and strength are basically what they used to be."

"Well then...we have it in the bag. There's...no way we'll lose to Undine."

Aquarius didn't sound too happy about our assured victory. And I could understand why. If she were the type to celebrate the murder of her best friend, she wouldn't have been the guardian of the lake for hundreds of years.

She was no fool, though. She knew that leaving Undine as is would pollute the water of the Demon World beyond restoration, bringing it to its eventual end. The fact that she kept on protecting her only went to show how deep their bond was.

And I understood how she felt. If it were me, and Echidna or one of the Guardians were in a destructive frenzy, I'd probably seal them away and look for a way to make them better. Speaking objectively, it was easy to say that choosing someone you loved over the world, or risking the world to save someone you loved was sentimental nonsense, but that wasn't how people worked. Sometimes, you knew someone you simply cared that deeply for.

"Aquarius."

Her shoulders quivered at the sound of my voice.

"I...I know," she said, and finally nodded with a look of resolve in her eyes. "Trust me, I know."

"Let us defeat Undine," she continued. "Like I said before, I can't go too far from the lake, so I'll need you to ask Queen Echidna..."

"Hold up. Were you even listening to me?"

"What do you mean?" she replied with a furrowed brow. She probably wasn't expecting me to argue her out of defeating Undine.

"I told you already that Demon Queen Echidna doesn't like sacrificing people."

"She's a Demon Queen against violence, huh?"

"She's a Demon Queen against violence," I confirmed.

Demon Queen Echidna was a fool. Definitely the most foolish of all the people I'd encountered. Though it pained her immensely to do so, she invaded the human realm in search of the Wisdom Stone to save her home. And when she invaded, she demanded that her forces cause as little death and destruction as possible. And in the end, she gave up her chance to get said Wisdom Stone just to save my life.

She was also both incredibly greedy and incredibly naive, our Demon Queen Echidna. And would she allow us to kill Aquarius's friend in order to purify the world's water? Absolutely not. She would try her hardest to find a way to save her, first.

And I came to Lake Amia as Echidna's representative, which mean there was only one thing for me to say. "Listen, Aquarius. You need to stop firming up your resolve over making such a tragic decision, and start using your head. Tell me everything you know, and don't give up on saving your friend."

The Aquarius I knew always had on a big smile and was bursting with confidence. And she loved telling me about how that ideal British gentleman she endeavored to become would never lose their wit or humor, no matter how difficult the situation.

"When things are at their toughest and darkest," I began quoting her, "that's when you put on a bold smile and let the jokes fly. Isn't that what a British gentleman does?"

"...Heh. Haha, hahaha!" Aquarius was suddenly overcome with laughter, and she continued laughing deeply despite Mernes's strange looks.

Yeah, a smile suits you so much better.

"My, oh my! I never expected to receive a lecture on how to be a gentleman from you, of all people!"

"Sure have grown, haven't I?"

I tossed a piece of firewood onto the fire then looked out at the frozen surface of the lake which held Aquarius's dear friend like some kind of icy black cage.

"All right. Let's start figuring out a way to save Undine."