When I thought about it, I realized I knew next to nothing about Himatsuri Asami. She had no trouble speaking with my mysterious mother and she had run away from her own home. But that was all I knew. I had no idea what she was doing there or where she had come from.

No.

More than that, I didn't even know if she was the real Himatsuri Asami.

That was a shocking truth, but I couldn't stop thinking.

After stopping near the water's surface, the Siren took in a dep breath and opened her lips just a crack.

A high-pitched whistle exploded out and my entire body, down to the fingertips, stopped moving.

Was this the Siren's song!?

I couldn't support my body, so I slipped from the building wall and was once more swallowed up by the current. The only upside was that my fingers froze in place with the smartphone in their grasp. If I had let it go in the surging water, I never would have seen it again.

But what was I supposed to do?

I couldn't swim like this. Nor could I breathe properly. On top of that, I felt something like a solid gummy hitting my arms and legs in the muddy water.

Were those the parasites? The Remoras!?

They had not managed to actually attach themselves yet, but it was only a matter of time!!

"…Gh, bh…"

I could not even scream with control of my throat taken. Was it all over? Would I suffocate in the water and have my body infested with strange leeches?

But just then, something as large as a small island rose up below me.

It skillfully supported me so I did not roll off in the wind and current.

"What did I tell you? I will give you permission to speak."

"Bwah!? Leviathan!!"

"That Siren has the twisted power to submerge an entire city in this lost sea. You should have known what would happen to your mind if you challenged her without my support."

Dammit…

Even after all this, I had to rely on someone else's power, just like I was running away from home again!

"On the other hand, dragging the Siren herself down here is deserving of praise. Leave the rest to me."

"…What are…you going to do?"

"She originally belonged to my organization. It was my failure that led to this chaos, so I will punish her myself. I will end this by crus.h.i.+ng her with my teeth. That is my duty."

"Do not feel bad. This is a matter of my organization. No matter how much blood might be shed, you need not dirty your hands. You continue working toward your ideal."

Was that how it worked?

Was that acceptable?

Was I…afraid of dirtying my hands? Was that why I claimed to be a pacifist? No. Who did the dirty work wasn't the issue. I had wanted to see humans and Archenemies getting along. It would all fall apart if I rushed to a conclusion and doomed an Archenemy to a sea of blood! Isn't that how it's supposed to work!?

I realized the truth at the last second.

And I worked to stop it.

Simple and heroic anger was toxic. The more you wielded violence, the more pleasure you would feel. The crus.h.i.+ng weight of the guilt would come later, so you would search out a new target to distract yourself from it. Once that began, you could never stop.

"You can't…do that."

"Why not?"

"Leaving this to you would be the same as turning a blind eye to the Bright Cross so they could handle all the dirty work."

The Leviathan fell silent for a moment. And then it spoke.

"If you reject every course of action, you will quickly find no path forward in your life."

"…I know that."

"But I will respect your decision. You have one chance. If you fail, then I will end it. So do not worry about what happens afterwards. Give it your all."

I couldn't quite tell if it was trying to encourage me or threaten me.

I did not know what Himatsuri-san's goal was here. Or even if that really was Himatsuri-san. Was she taking on someone else's ident.i.ty, or was someone else taking on her ident.i.ty? I knew nothing here.

And what was it I simply could not back down on here? It was not some stupid macho desire that confused punishment with justice. What did I really need here?

To return the Remora-infected people to normal.

To ensure no one would be taken here again.

To end this conflict and confrontation with my stepmom.

…I would not take no for an answer. No matter what, I would make sure those three things happened. Anything else would count as a loss for me.

"I will support you," said the Leviathan. "We will be unable to speak, but the link will remain. I will do the best I can to fight the Siren's interference, but I do not know how successful I will be. So be careful."

Strength returned to my numb and unmoving fingertips.

I grabbed the nail file I had used as a flathead screwdriver.

I wasn't afraid of the floodwaters. I could reproduce this in the simulator.

"I a.s.sume you can hear me, Leviathan. Take me to the Siren."

Even without a response, I could tell it could hear me.

"Her brutality is concentrated in that song. That's how she sends people to this glowing ocean and messes with people's heads."

It was unclear how she worked with the Remoras, but I doubted the leeches were carrying around headsets. I guessed the airborne Siren located a target and used her song to instruct the Remoras to attack it.

Or maybe she could directly control them with her song.

"…So I'll settle this by taking out the Siren's throat. I don't have to prevent her from speaking altogether. Just like treating a cavity or swollen tonsils can change your voice, a small wound should take away her optimal voice quality."

I knew this was a cruel thing to say.

It was like attacking the Achilles' tendon of a man whose life centered on playing soccer, but claiming it was okay because he would still be able to walk once he healed. Being taken from the forefront was the same as taking his entire life from him.

But that was a compromise I was just barely willing to make.

As long as I could end this without taking anyone's life.

I of course knew she was not going to like it.

The Leviathan's giant body parted the floodwaters, shot straight toward our target with enough force to split the sea, and approached the Siren floating just off the water's surface. Her eyes wavered up and down for just a moment. She was not sure who to attack: me or the Leviathan.

Normally, she would be more concerned about the 30m shark than a puny human.

Just before collision, the Siren's eyes dropped down.

…Now!!

"Ooooahh!!"

With a yell, I ran across the Leviathan's back and leaped forward. And I held the nail file I used as a flathead screwdriver so I could stab the center of the grip into her slender throat.

Just then, the color gold fluttered around.

I had no idea what happened.

I simply felt a heavy impact pa.s.s through my entire body. It came from my jaw. Something had hit me there. My vision blurred, I lost balance in midair, and I fell into the water.

…d.a.m.n.

I had come so far yet I was dealt with like an afterthought…

My head was shaking.

I fought with my unfocused eyes to pull together an image.

I saw a ceiling.

As soon as I realized I was in the guest room of my mother's apartment, someone peered down at me.

"Oh, did you finally wake up?"

"…Himatsuri…-san…!?"

I wanted to jump to my feet, but my body refused to move.

What had happened back there? Was Himatsuri-san really the Siren behind all this? Or was someone else pretending to be her? If so, what was the connection between her and the Siren!? They wouldn't do that without good reason!!

"What's the matter? I wasn't there this time, but were things especially bad? Not that risking your life in that shark's place is ever going to be pleasant."

…What did this mean?

Was she playing dumb? Even though we were the only two ones in the room? If not, did she really not know what had happened? But how could she not? Did she lose her memories of what she did as the Siren?

As far as I could tell, Himatsuri-san was the same as always. I guess I would say it seemed unnatural that she did not respond at all to what had happened.

"There is…something I want to ask you."

"What is it?"

Puzzled, the beautiful girl, who had cabaret girl blonde hair and a champagne-colored dress, tilted her head.

"…How did I get to the apartment? I entered the glowing ocean from my actual home."

She must have sensed an odd nuance in that because Himatsuri-san narrowed her eyes somewhat. And since she stood on the side of my mom, Magatsu Taori, it was not necessarily a welcoming light in her eyes.

"I don't know. Taori-san carried you back, but didn't say anything about it. So where was the exit this time?"

Since my stepmom, Amatsu Yurina, had been curled up at home, it should have been somewhere in that house.

I found it hard to believe my mom would approach that house now. Not to mention setting foot inside. So had the Leviathan set up multiple exits around the city?

…That was probably the case.

I didn't know how many people were being dragged there by the Siren's song, but if there was only one exit, they would all have to rush there. So what about when it was that industrial complex's blast furnace or that inn's detached room? Those places were off limits and Himatsuri-san and I had only managed to sneak out with Maxwell's a.s.sistance. Looking at the reality side of things, it would have made the news if 100 or 1000 outsiders appeared there. Besides, where were the Siren and Leviathan getting in and out? It seemed like multiple exits was the best way to think about this.

But I doubted I had left the exit on my own after pa.s.sing out.

So…had the Leviathan saved me?

"Oh, right. What happened to the Leviathan!?"

"Eh? That giant shark?"

Himatsuri-san sounded somewhat creeped out. That reminded me that she had not been with me at the aquarium, so she still saw it as a man-eating shark. She wouldn't know that it could speak human language.

But what had it done after pus.h.i.+ng me out of the "today's exit" door? Had it returned to reality through a large aquatic gate near the aquarium? I doubted it. If it was to be believed, then its greatest enemy had finally been brought within reach, so would it really turn tail and run?

Something had to have happened.

Himatsuri-san was here and with no memory of being the Siren. That was a mystery in and of itself, but something must have happened. They would not just have parted ways peacefully.

"…Himatsuri-san."

"You look pretty grim. Did something really happen?"

I breathed in and out.

If she was simply playing dumb about being the Siren, then I might die here. Being nearby was enough for her song to scramble my brain and her straight claws had shredded the thick rubber rescue boat. That was superhuman ability, so my windpipe would be a simple task.

"What does the word 'Siren' bring to mind?"

But I still said it.

I couldn't put it off any longer. The Siren had attacked my stepmom and she could attack anyone next time. I couldn't let that kind of tragedy happen again. I wasn't just an observer. More than half of the fault for what happened to my stepmom lay with me.

So it was my turn to protect.

I would protect my parents, my family, my neighbor, and everyone else I could think of.

When she saw the look in my eyes, Himatsuri-san fell silent and sighed. Perhaps due to her manicure, her beautiful nails s.h.i.+ned like a blade as she moved her fingers.

I felt my heart pound extra hard in my chest.

But I did not take my eyes off of her.

Then she pulled something from her cleavage and tossed it to me.

It was a smartphone.

I thought I had destroyed hers and thrown it into the floodwaters to escape the Leviathan, so had she gotten a new one?

"Check the screen."

I did as she said and saw a photo alb.u.m management app was open. She had apparently restored the data from a backup. A single photo filled the screen.

It was from a bit too close up, suggesting it was a selfie.

The limited s.p.a.ce was filled by two girls.

…Two?

Yes, that was right. It must have been an older photo because the two blonde girls looked my age or a little younger and they fit themselves in the same photo by pressing their cheeks together.

"This is why I've run away from home. It's all very silly, though," said Himatsuri-san. "Her name is Minaki, written with the characters meaning beautiful, cry, and happy. I was told she was a relative and I had always believed it. We only met once or twice a year, but I always looked forward to the Bon Festival and New Year's because of it."

Nothing about it seemed odd, but one phrase threatened to tear it all down.

She had said, "And I had always believed it."

"Minaki was apparently an illegitimate child. She was my younger sister."

All sound vanished.

Every last decibel in the room faded away.

"Once I knew the truth, I could find all sorts of clues from the past. There was a cousin and an aunt, but I had never seen the uncle. These were supposed to be family reunions, but Minaki and her mother always showed up late so they missed the main gathering. …And I had never once seen Minaki speaking with my mother."

…This was a family twisted in a different way from mine.

There was no point in comparing the two…

"You can say adults don't play fair as much as you want, but actually seeing that reality before your eyes is so much harder." Himatsuri-san placed a hand on her forehead. "…My father was a workaholic. He increased his social status to fight back against society and earned lots of money to fight back against his family. He put himself first and there was no benefit for us. So it was a shock to learn he had given his love to someone else, but that was honestly a trivial matter. I mean, without that mistake, Minaki never would have been born. It was a complicated feeling, but I could have put up with that."

"What I truly couldn't forgive was that he was giving money to Minaki and her mother. Those visits I so looked forward to were really so he could hand over a bunch of cash. …That solved it. If she had wanted to, she could have brought it to court and torn my family apart, but my father solved it by tossing some cash onto the table looking as irritated as can be. That wasn't love. I couldn't understand it. To him, humans were no more than status symbols, like a foreign car or a brand-name bag! It was only because Minaki and I had grown too much that our mothers were considered a mistress and a wife. He had plenty of other people, but they were just like brand-name bags he bought just to buy and threw into the closet without even opening the box!"

No one would talk about that. Not Himatsuri-san's family and not Minaki-san's.

So how had Himatsuri-san learned about it?

…That was obvious: she had seen it for herself.

This girl had been more important than a friend and she only saw her twice a year: during the summer and during the winter. While excited about finally getting to play with her again, she had seen it.

Perhaps through a cracked door.

She had seen familiar people holding the worst possible conversation, she had seen people she cared about only able to bite their lips and accept it, and she had seen the trembling fingers reaching out toward the cash slammed violently onto the table.

And that could have been her.

Those people were like abandoned bags or shoes, some arbitrary order had decided who was the proper family and who was the mistress's family, and the two sisters were forced to keep their heads down by their mothers.

"Um."

I had no idea what to say. I could only pray that Himatsuri-san met someone like the Cla.s.s Rep was for me. Maybe that was who my mom was.

All I could say was…

"…So are you not an Archenemy yourself?"

"Isn't that obvious? I'm just a human. If I had that kind of power, I would have killed that man already. To free us all."

When speaking in terms of her mother, she had called him her father, but now she just said "that man".

"…It must be Minaki's mother. That has to be why Minaki has that power. And if they do have that kind of power, I'm impressed they haven't used their claws or fangs on him."

…Ah.

I finally, finally felt like I had reached the heart of the issue.

The situation was not actually what Himatsuri-san thought it was. Minaki-san had thrown the city's people into the glowing ocean and had gotten Himatsuri-san herself involved.

But what was it the Leviathan had said?

Sirens belong to the sea, but they fly through the sky. So they might have a connection to beings on the land. The Leviathan's group had not cared what the Calamity did to the surface. But the Siren could not just ignore it. So she had challenged my stepmom who had put together Absolute Noah and she might be trying to find another way of overcoming the Calamity.

How could this be?

In that case, what was it the Siren - Minaki-san - had wanted to protect them by betraying her old sea organization, challenging Absolute Noah, and making an enemy of actual demon lords like Lilith and the Leviathan?

No matter how much she flapped her wings, her freedom had been taken from her and her head held down.

She was a bird trapped in a cage.

But had she still been trying to protect Himatsuri-san's family!?

…How?

How much would you have to care for someone to make that kind of decision? The slightest dark emotion or desire for revenge would have led her to abandon them. She would not be destroying them herself. It would be the Calamity destroying the Himatsuri family. If she used that excuse, it would have ended at the very first step and nothing would have happened.

But the Siren refused to accept it.

She would not allow the Himatsuri family or the people who lived there to drown in a sea of blood and suffering, no matter who caused it to happen. And to prevent it from happening, she had directly challenged a giant organization controlling the world from the shadows.

"…She looked forward to it."

"No matter what the real reason was, Minaki-san still looked forward to seeing you, Himatsuri-san. She still looked forward to laughing and playing with you. That's the only explanation!!"

"Wait, what are you talking about!?"

…After all, there was no darkness at all in Minaki-san's photographed face. If she was putting on an unwilling act, there would have been something there, but I couldn't see any hint of it on her face on that cheek-to-cheek photo.

Who was right?

Who was wrong?

Himatsuri-san was not the Siren. So was Minaki-san still in that blue battlefield? The Leviathan had to have gone right back into those floodwaters after pus.h.i.+ng me back to reality.

How much time had pa.s.sed since then?

The Siren could not breathe underwater and the black smoke from the fires had filled the sky with carbon monoxide. Minaki-san could only remain just above the water's surface, making her the perfect target for the Leviathan. And the Leviathan would not overlook that opportunity. It would finish her off.

"Maxwell, Minaki-san is in danger. Is there any way to go save her!?"

"No. You can only access those uncertain coordinates once a day. You lack the rights."

Dammit!!

But Minaki-san had to know she was at a disadvantage. That was why she had remained above the clouds to hide in that safe zone out of the Leviathan's reach.

In that case…

"Minaki-san must have returned to reality. That's the only way for her to escape the Leviathan's jaws."

She had to have returned.

The Leviathan was unstoppable there but restricted to an aquarium tank back in reality. You might be at risk in the ocean, but it could not reach you on land. Reality gave you better odds of protecting yourself and healing any wounds.

"Where is Minaki-san in reality? If she can move back and forth between the two areas, she must have some kind of hideout. And inside Kukyou City. She has to be there."

Of course, I had to think of Minaki-san as a threat. Whatever her goal may have been, she had used her song to send quite a few people to that glowing ocean and she had infected them with the Remora parasites. She had also injured my stepmom.

I had to keep Minaki-san from acting before the Leviathan got to her and I had to prove something.

Prove that she had to pay for her crimes, but there were ways of doing that without killing her!!

"Wh-what are you talking about? Minaki is in danger? Was that girl dragged into the water too!? Hey, what do you mean!?"

Himatsuri-san grew pale and grabbed at me.

She was looking at this the wrong way around, but I felt like I understood why Minaki-san would risk her life to protect Himatsuri-san. This was the kind of person Himatsuri-san was, so Minaki-san had wanted to return the favor. Even if they had different mothers, they were still connected by blood.

Telling her the truth would be hard.

Minaki-san was behind this and she was doing this awful thing for Himatsuri-san. And since she had put Himatsuri-san in danger, Minaki-san may have lost control.

However…

"Warning."

Maxwell sent a silent message.

"If Miss Asami has not used up what Mrs. Yurina called the 'one-way ticket', she might access those uncertain coordinates to search for Minaki. She will meet the same fate as Mrs. Yurina when she stayed longer than necessary to search for you."

"Kh."

Even Archenemy Lilith had barely survived. And now that the Leviathan and Siren were actually clas.h.i.+ng, the battlefield might be even more dangerous. That could be the worst possible place for a mere human like Himatsuri-san.

And if she entered a puddle herself, I could not go save her since I had already used up my one-way ticket.

…Was this the end?

As cruel as it was, I could not let Himatsuri-san die. I would make sure she stayed with me.

"Himatsuri-san, listen carefully."

"Wh-what is it…?"

"I will tell you the full truth of this incident. And a lot of it isn't going to be easy for you to hear."

"You're…kidding…?"

As Himatsuri-san listened to my explanation, she held a trembling hand to her mouth.

It must have been hard to believe.

Her eyes widened, but she did not stop me.

"I don't believe it. Minaki was so kind and she never raised her hand against our cruel father…"

"Being kind and whether or not she used her power are two different issues. In fact, I think it was because she is more human than any of us that she couldn't abandon you."

"But…that's right. What about those parasites? Minaki would never do that to other people!"

"I don't know about that. Maybe she had some reason to choose those specific people, or maybe she's lost control."

Either way…

"If the Leviathan ends this, we might lose any possible chance of removing those Remora parasites. So the only way to save them is to contact the Siren ourselves. Without killing her, of course."

"Of course we aren't going to kill her!!"

Himatsuri-san was rightfully angry. Minaki had had her head held down by both of her parents and the circ.u.mstances of her birth had prevented her from spreading her wings, so Himatsuri-san must have appeared so bright to her eyes.

"I know what I have to do. I have to dive down there and capture Minaki."

"You can't escape the Leviathan like that. That shark is more comfortable in that h.e.l.lish battlefield than in reality. And the Siren wouldn't place her base anywhere within the Leviathan's reach. If we want a chance to speak with her, it would be better to lie in wait at Minaki-san's hideout in reality and capture her when she appears there."

"We can't wait that long!! Minaki could be dying as we speak!!"

"The Leviathan might use you as a hostage!!"

I completely made that up.

I just needed something to prevent Himatsuri-san from succ.u.mbing to her emotion and diving into that glowing ocean.

But for some reason, I felt like the puzzle pieces had all clicked into place.

"Minaki-san's biggest weakness has got to be you, Himatsuri-san! She created that glowing ocean as the game master and the Leviathan intervened as a hacker. If you go where the Leviathan can reach you and keep you from acting, you'll just be wrapping the noose around the Siren's neck!!"

…Wasn't that exactly right?

It was true the Siren had created that place. But Minaki-san had no reason to bring Himatsuri-san there. Not even 1% of one. Meanwhile, the Leviathan had interfered to create exits from that glowing ocean. What if it had used that same interference to bring Himatsuri-san to the battlefield? That was only a plus for the Leviathan!!

That may have been logical.

It may have been the right decision.

But it made me want to scream at the Leviathan:

You piece of s.h.i.+t shark b.a.s.t.a.r.d!! You think that shows an understanding of human emotion and you still have the nerve to lecture me on my family affairs!?

"Please understand. The best way to contact and rescue Minaki-san is in reality where the Leviathan can't interfere. And I doubt my words can reach her, since I'm her enemy. I need your words. There's no other way!!"

"…But what do we do?"

Himatsuri-san consciously took a deep breath and even I felt a little calmer.

"I know Minaki has to be in this city to spread her song around. But I have no idea where her hideout would be. Do you have any ideas?"

"Did nothing like that come up in your conversations with her? Did she ever mention creating a secret base or having some location with sentimental value to her?"

"…Hmm…"

At times like this, people could prioritize emotion over practicality. I had experienced that a few times with the Bright Cross and Archenemies. Humans were not capable of acting logically when on the verge of death. The closer we got to death, the more we had to face our own souls head-on.

"Himatsuri-san, do you mind if I make copies of all the photos on your smartphone? I'll delete them once the work is done."

"Eh? Go ahead. It's a bit embarra.s.sing, but this isn't the time for that."

"Maxwell."

"Sure."

I copied all the photos on Himatsuri-san's phone to my smartphone. There were about 23,000 of them. They were probably a representation of her entire life carried over through several different phones.

"Find any photos with Minaki-san in them and scan her face. Construct an expression palette and rank them from positive to negative. Pay especial attention to anything near the water."

"Sure."

"F-facial recognition can read emotions these days!?"

"Nowadays, vending machines commonly include programs that use a camera to track your eyes and expression to determine which products caught your attention. Maxwell."

"Sure. Task complete. The location that provided the target, Minaki, with the most positive emotions would be the Himatsuri home, but that likely has no bearing on this incident."

"…Minaki, you idiot…!!"

Himatsuri-san was too overcome with emotion to speak properly. This was not the answer we were looking for, but it may have been necessary.

"When narrowing the search down to only include waterside areas within Kukyou City, I have found a second candidate."

"What is it?"

"Sure," said the social media speech bubble. "Kukyou Dam in the mountains. That is most likely where Siren Minaki is hiding."

We had no time.

Himatsuri-san and I left my mom's apartment and made our way to the mountains on foot. Night had fully fallen. Groups of college students and office workers were heading out for the night, as if to prove that ignorance of this incident was bliss.

"Let's call a taxi. We won't make it in time on foot."

"That sounds great, but it will only take us to the foot of the mountain. Ask them to take us to the dam at this hour and we might get reported to the police for attempting a double suicide."

Himatsuri-san must have started up a ride-sharing app on her smartphone instead of raising her hand. It apparently used the phone's GPS signal because a black car smoothly came to a stop in no time.

"Wait, this isn't a taxi… Is this a hired vehicle!? That costs several times more!!"

"Does it? They're pretty much the same thing. What's the difference?"

…She really was from a rich family. I had never ridden something like this before. And didn't you already need a contract for a hired vehicle like this?

I had been planning to be a man and pay for the ride or at least split the bill…but this crushed any hopes of that. Thinking back, I had almost always used a bicycle or gone on foot when fighting the Bright Cross with Itou Helen. I was apparently part of the petty bourgeois even when my life was on the line.

I nervously climbed into the backseat after Himatsuri-san and the car smoothly left once more.

Then my smartphone vibrated.

"You have received a message from Kukyou University Hospital. Mrs. Amatsu Yurina's treatment is complete and her situation is stable. There is no risk to her life."

"I see. That's good… Wait, what about Erika and Ayumi?"

"I have not received any word of them being injured."

"Not that. They were left to their own devices after seeing our stepmom injured with no explanation. Maxwell, send them an email immediately! Tell them I know what's going on with our stepmom and tell them not to go on a rampage!!"

"Sure. …But do not blame me if this has the opposite effect."

I didn't care if they got mad at me here. I didn't want to create any more enemies for isolated Minaki-san. It was hard to say even I was on her side. I certainly couldn't ignore that she injured my stepmom.

But even so…

Couldn't the world have been a little kinder to that Siren?

The hired vehicle came to a stop at the foot of the mountain. That would seem a little odd since there were no famous restaurants or sightseeing spots here, but there was no helping that. And perhaps because it was a luxury hired vehicle, the driver did not ask any questions.

We got out of the car.

A while after it drove off, Himatsuri-san asked me a question.

"Could you tell a difference in how the ride felt?"

"To be honest, no."

We laughed together and then looked to the mountain covered in darkness. I had seen more than enough of it for a lifetime and it felt different again from when we visited that inn before. It was a bizarre scene that I never would have seen in a normal life. My spine tingled from the threat of nature. It was different from the fear of an abandoned school or hospital and it was not quite like seeing the sea soaking up the darkness of the night. We were about to go there. And we were nothing but puny humans who had cast off our claws, fangs, and fur.

"Let's go."

"Yes."

We nodded to each other and started up the mountain road. Even if it had been necessary, I had to wonder what the people were thinking when they carved away the mountain slope and covered it in concrete and asphalt. It felt like walking up the road was the same as entering some forbidden area.

It was true the Leviathan might have a hard time targeting us on this artificial reservoir lake cut off from the ocean. But curling up in this darkness all alone seemed like it would be enough to break you.

I glanced over at Himatsuri-san.

I was glad she was with me. If I had been alone, my mind may have been worn down to the breaking point before I reached the reservoir lake.

We walked up that ominous and evil mountain road.

All so we could reach the ma.s.sive structure that humans had so insolently built.

"I can see it…"

Himatsuri-san sounded as worn down as I felt.

We saw the straight lines of something artificial mixed in with the curves of nature. It felt like an indescribable blasphemy. The people who had seen it through to completion must have had iron wills. It was beyond me how they had not broken partway through.

"…But where in the reservoir lake is Minaki-san?"

The reservoir lake was quite large. One trip around the perimeter would make for a light jog.

"Maxwell, what about the dam itself?"

"It is always a possibility, but it would not be very realistic. Dams are as serious a target for terrorists as airports and TV stations, so they are made with a high level of security. They are not conducive to infiltrating from the outside."

"Then it would be a structure near the reservoir lake. Search for deserted mountain cabins or campgrounds."

"Sure. Including grill stations and agricultural water pump stations, there are 43 in all. Of those, 19 meet the minimum requirement for living there."

"No, the Siren should be able to freely take materials and food from the glowing ocean. We can ignore the need for water, food, a bath, and a bathroom. Rerun the search while focusing exclusively on whether or not it provides shelter."

"Sure. There are 25."

"25 minus 19. If she was trying to trick us, she'll be in one of the 6 you just added. But a runaway would be starved for information. The battlefield has no power and you couldn't access reality's news from there anyway. Plus, the signal isn't going to be great in the mountains. Check the support situation."

"Sure. Based on the service area map from each company, 2 of the 6 would not receive TV or radio signals due to the high-voltage lines of a transmission tower. The geographic conditions for 3 would leave them unable to connect to the internet. A cellphone reliant on the communication towers would receive no signal."

"Then there's just the 1 that has both TV and the internet."

We followed Maxwell's directions to a villa built by a rich person who liked hunting. They had built it outside of the general villa area, so they must not have expected the others to accept a hobby that used real guns. However, they only visited it a few times a year, so it was usually abandoned. If you could avoid the home security sensors and the manager who came to clean the place once a month, it was yours to do with as you wished.

"If they only use it a few times a year, they wouldn't bother stocking food there. That would be why it wasn't on the initial search."

"What a careless location," said Himatsuri-san. "One reason villas tend to be built together is to share the cost of keeping guards stationed there. The owner is probably trying to lure criminals in."

"If it's self-defense, you're allowed to shoot, even if it's a fellow human being. They spice up their life by dreaming of the day it finally happens."

That sent a chill down my spine. I had thought I had seen enough cruelty for a lifetime with the Bright Cross.

And that was exactly where we were going. We were so deep in the mountains that our connection with Maxwell could be lost at any time. We could shout, but no one would come to look for us. And we could call the police, but we would not hear any sirens for quite a while.

"…Himatsuri-san…"

"You're a stranger, so you would be in more danger on your own. Without me, I doubt you would be able to talk it out. Also," said Himatsuri-san on the moonlit lakeside. "This will be fine. As long as this is the Minaki I know."

Yes, we had to do this.

We would end this here. We would capture Minaki-san the Siren, prevent her from doing anything more, and have her return the Remora-infected people to normal. That would also end the attacks from the Leviathan.

It was all about what was convenient.

A great wall stood in the way of the ideal I had proclaimed. But I had still decided I was doing this, so I had to dive into the danger.

The villa was ostentatiously located on the lakeside and built to look like a log house. It looked like something out of a picture book, but that was what made it seem so unnatural. Were they not afraid of people coming in the middle of the night while making a lot of noise? Or was Himatsuri-san right and they were waiting for the idea to cross some villain's mind?

I also saw something else unusual.

There was a faint light moving within a second-floor window. It was not the room's light. It was smaller. It was probably a handheld light or camping lamp.

"There's someone there."

"Let's check it out."

If we were wrong, the Siren was not there, and a rich person starving for excitement was lying in wait with shotgun in hand, we would get shot the instant we set foot inside. We were crossing the threshold into danger whether we were right or not, but that extra risk sent my heart racing.

"Maxwell, check the status of the home security. If necessary, neutralize it. Without the call center noticing the oddity, of course."

"No. The sensor on the back door has already been bypa.s.sed, so it is effectively neutralized. You can enter through there."

The villa's owner wouldn't do that…I hoped. We exchanged a glance and slowly walked around to the back.

"Maxwell, any light would be risky here. The backlight would stand out, so I'm going to turn it off."

"Sure. I will vibrate the phone if I detect danger. I will use multiple vibrations like Morse code to inform you what kind of threat is approaching."

I stuck the smartphone in my pocket and Himatsuri-san and I touched the back door. We slowly turned the k.n.o.b and pushed the door open so as not to make a noise.

We slipped in through the gap.

I then realized I had screwed up by not having Maxwell determine the internal structure from the architect or construction company's server. I relied on the moonlight entering from outside and traced along the wall with my fingers to continue on. The mysterious light had been on the second floor, so we first moved to the stairs.

I felt a tugging on my jacket. Himatsuri-san was trying to tell me something, but I could not even see her expression from this close. Once I squinted and tried to see it, my eyes must have adjusted to the darkness because the surrounding silhouette came into view.

A tall rectangular part of the wall was missing.

Were the stairs through there?

The two of us went there and we did indeed find the stairs leading up. I felt along them and found they were made of wood, so they would probably creak louder than a normal floor. We didn't have time to worry about looking silly. We used our hands as well as our feet to distribute our weight and slowly climb up.

When I peeked up at the second floor, I saw a short hallway with a few doors on either side. The layout was different from the first floor, so there were no windows and thus no moonlight. A thick darkness hung over the place. I could not tell exactly how many doors there were. I knew how dangerous it was, but I was briefly tempted to rely on my smartphone's backlight.

But that was what convinced me.

Minaki-san the Siren had succ.u.mbed to this darkness as well. That was why she had relied on a light that could be seen from outside.

This darkness was nothing to fear.

It was a weapon that was guiding us.

Once I thought about using the darkness, my view of the situation changed entirely. I could tell there was just one door with a faint light leaking out from below it. It was not much, but it was as bright as the guiding north star to our darkness-adjusted eyes.

Slowly.

Very slowly, we approached that door. We pressed against the wall on either side. Despite the darkness, words were unnecessary. I nodded and I was confident Himatsuri-san had done the same.

This was her job now.

Only she could do this because of the time she had shared with the girl inside.

I heard her breathing in and out.

And then she spoke.

"M-Minaki…?"

She did not even knock and it was a quiet voice.

A short silence followed.

And then…

Five fingers broke through the center of the door at head height.

To be honest, it happened too quickly to react. I fell on my b.u.t.t and pulled the smartphone from my pocket.

"Himatsuri-san, stand back!!"

"No!! Minaki!!"

The slender arm pulled back in, but then it split the entire door apart. When I watched the door break apart, I felt a fierce tension spiraling in the depth of my gut instead of my mind. Had we been too naïve? Should we have viewed her as the violent Archenemy who had caused such a largescale incident!?

"Maxwell, do your best to simulate the Siren's next action. Include the predicted vector route and display it over the real scene!"

"No. I have too little information for a simulation."

Dammit!?

Without Maxwell, I was just a high school boy. Even if she did not specialize in direct combat, she was still an Archenemy. I doubted I could win this fight. Could I at least give Himatsuri-san time to escape…!?

My fear and resolve meant nothing.

With the unsteady light source of the camping lamp dangling from one hand, a silhouette did not hesitate to step out into the hallway. She was holding a light, yet that only emphasized the shadows and made her look more monstrous.

Was this really the person in that photo?

That girl who looked identical to Himatsuri-san?

"Minaki…"

She didn't have to, but Himatsuri-san still tried speaking to the figure. The Siren moved her eyeb.a.l.l.s instead of her head to determine the priority of her prey.

I slowly rose to my feet and picked up a piece of broken wood as quietly as possible. I also started up my smartphone's camera app and made sure to prepare the flash.

Of course, I could not defeat an Archenemy just by catching her off guard.

But she held a lamp using fire, not a flashlight. I could at least hit her wrist and make her drop that. If I aimed for the confusion as the fire spread at her feet, it was possible I could give Himatsuri-san time to flee.

"What are you doing here, Minaki!?"

I judged the timing. This wasn't the cleverest plan in the world and she may have already noticed what I held behind my back. The figure took another step toward Himatsuri-san.

"Asami…-chan…?"

Her voice sounded rusty.

But when I heard it, I stopped myself at the last second.

"It's…really you? Not some disguised a.s.sa.s.sin…?"

"Minaki, you idiot!!"

Himatsuri-san did not hesitate to hug her. She moved right into the lethal range of the Archenemy's claws and fangs. Minaki-san was trembling and I could not see her face from my perspective. But when she very slowly hugged Himatsuri-san back, I saw no harmful strength in her arms.

…We had made it in time.

That was all I could conclude. It might not look like much, but this was a miracle we had caused ourselves.

She was not a monster.

Himatsuri-san had proven it.

Minaki-san the Siren was more overwhelmed than emotional Himatsuri-san the Human. Minaki-san did react much to anything. Although I had no way of knowing if that was due to the constant tension of her situation or if she had always been gentle.

"Asami-chan, um, are you quite done yet…?"

"Not yet! I won't let you get away with worrying me like that!! Stay seated there! Why are you perfectly fine when I'm bawling like this!?"

"Ah, ah, ahhh…"

Minaki-san looked troubled, but she showed no sign of forcing matters with her Archenemy strength. In fact, I could see a kind look in her eyes as she looked Himatsuri-san's way.

I could tell they were family.

No matter how complex their circ.u.mstances were, they were definitely blood-related sisters. Social status, their family's category, and the adults' issues could not change the fact they were sisters through and through.

"What's so funny!? Why are both of you smiling!? Taori-san's boy, you sit yourself down here too!"

"Wahh!?"

When Himatsuri-san focused on me, the pressure on Minaki-san lessened just a little. It looked like it was about time, so I got down to business with Minaki-san.

"About the Remoras…"

"Right."

"When did you two get on the same wavelength!?" protested Himatsuri-san. "Why am I the only one left out!?"

…I began to wonder if those sisters had chugged a bottle of beer when I wasn't looking, but continuing on like nothing had happened was a talent of mine!!

"I only asked everyone to search out and eliminate people connected to Absolute Noah," said Minaki-san. "The list of names I had was horribly incomplete and, looking back, it might have been a decoy list left for someone like me to find."

"Yes, it is hard to say. Not even I know how many people my stepmother has hidden in this city."

"Oh, there's no need to be all polite."

"When you look like twins, it's hard to know how to approach you. This way is easier."

Himatsuri-san had said she was her younger sister, but she seemed older than me either way.

"Now, when you say 'eliminate', what do you mean? …Like kill them?"

"This might be hard to hear."

"Go ahead."

"Instead of just killing them, it causes a greater panic and more damage to keep them alive and have them infiltrate the organization. From what I've heard, Absolute Noah isn't the friendliest environment, so I thought it would be pretty fragile if you made some internal cracks. Having them bring out some secret doc.u.ments would have been best, but even if they were caught, it would still have everyone there suspecting everyone else."

Meanwhile, Himatsuri-san puffed her cheeks out like a child.

"…I haven't said anything this whole time."

"You're free to speak whenever you want. So what is it?"

"It's all you two! Just so you know, love at first sight always ends in failure. And I won't let my little sister go through that!!"

"Since when were so adorable!? Did you mentally revert to childhood!?"

"Ah ha ha. Onee-chan, um, always stays right by my side when we're together."

If she was always like this, it would have to be exhausting. She probably had her reasons, but it may have been for the best that they only met twice a year.

Anyway…

"Let's just leave the clingy sister to her jealousy… Now for the real issue here: do you know how to remove the Remoras from the infected people?"

A yes or a no here would change things dramatically. And if it was no, I would never be able to forgive her for what she had done.

"About that…"

But Minaki-san looked troubled.

"The Remoras are Archenemies that attach to the hulls of s.h.i.+ps and keep them from moving."

"What about it?"

"If they just kept doing that, they would starve and die along with the s.h.i.+p. That's why they're made to attach and detach, like an on and off switch."

Some people would see that as giving up too soon and others would see it as a highly convenient biological weapon.

To me, this sounded like history's most horrific biological weapon. You could think about what to do after spreading it around the world and you could make course corrections if it did not spread the way you wanted. Plus, there was no vaccine or antibodies for it. It simply got inside the body, attached its suckers, and controlled the host, so even if someone was freed, they could always be infected again.

"But the Remoras aren't listening to me."

"What?"

"It's true there were people who were in the way if I was to secretly build a foothold in Kukyou City and it's true I ordered to have them attacked. I won't deny that. I intended to release them once I was done, but none of them will switch off…"

We had no way of immediately determining if that was true or not. But it was true that we had not known until now why exactly the Siren had infected the city's people with the Remoras.

"First the Leviathan, then the Siren, and now a Remora rebellion?"

"Hmm, I'm not sure." Minaki-san placed her index finger on her slender chin and looked up at the dark ceiling. "I feel like it all got so much more confusing once Leviathan-sama arrived."

"That duplicated the chain of command. We had left the main group, but Leviathan-sama is still the lord of the ocean. So when they're nearby, there's a good chance the Remoras don't know whose orders to obey and end up doing nothing."

"…Are you kidding?"

But thinking about it, would the Leviathan show any concern for the Remora-infected people when it was so focused bringing death to the rebellious Siren?

And weren't the Remoras parasites that attached to the Leviathan's body? I had heard that directly from the Leviathan.

But wouldn't it be able to use that?

If they kept doing damage to my stepmom's organization, wouldn't Absolute Noah strengthen their forces and attack the Siren for self-defense and revenge?

The Leviathan was the strongest on the sunken battlefield, but it would have a hard time reaching these inland mountains. And the same would be true of the Mermaids, Lorelei, and other marine Archenemies under its command.

So it was the Leviathan who would have gained from forces that could fight on land.

Had that b.a.s.t.a.r.d pretended to be falsely accused to throw oil on the fire!?

"G.o.dd.a.m.n that shark!!"

"No, wait. I'm just guessing. I have no real proof. Leviathan-sama might not be doing it on purpose and it might be something else entirely. It is entirely possible this is just the Remoras rebelling."

"Then answer me this," I cut in. "My stepmom, Amatsu Yurina, who you know as Archenemy Lilith, came back from the glowing ocean injured. I didn't see what happened, so tell me. …Who was it that hurt her?"

"The Remora-infected…people."

"Then was that something you ordered them to do? Did you tell them to kill my stepmom to carry out your objective?"

"No. I came here to attack Absolute Noah until they had to reveal their information on the Calamity. Then I could use that to search for a way of avoiding it other than their ark. Killing the person with the most information would threaten that and we could never work out a compromise if I angered them too much. I would never target someone that important. Even abducting her to get her to talk would have been too dangerous."

That left only one answer.

Someone had taken over the Remora's chain of command, pretended to be an ally, and secretly ordered them to attack my stepmom. And on that flooded battlefield, my stepmom would have relied on that demon lord who was an old acquaintance and powerful in the water. Rescuing me without my knowledge would have helped build up her trust.

In other words, it had used me to bring down my stepmom's guard and then had her attacked while she thought she was safe on its back.

"I'm going to tear that shark b.a.s.t.a.r.d's stomach open and drag out tons of caviar…!!"

"Calm down! And the old texts say Leviathan-sama is female, so that's really not funny!!"

"Then the fin! I'll chop off that giant-a.s.s fin and make a soup full of collagen!!"

"That sounds lovely, but please wait!!"

Minaki-san frantically waved her hands around to get me to cool down.

"B-besides, what does Leviathan-sama gain by attacking Lilith…no, Absolute Noah?"

"The individual Remoras don't gain anything either, do they?"

"Uuh…"

"And my stepmom already gave a reason for the Leviathan to oppose Lilith."

This wasn't something I could brag about.

In fact, I was kicking myself for not thinking about it earlier.

"I thought it was a harmless possibility once I learned my stepmom had only used it as a bluff to trick me, but the Leviathan hadn't forgotten."

"What is it?"

"There are different theories of which demons are in control of which of the Seven Deadly Sins, but Lilith and the Leviathan both control one. I think my stepmom had sloth and the Leviathan had envy. But since the number of demons reaches the double digits with only seven seats, they're all lined up there without any clear decisions. If that hurt the Leviathan's pride, it might want to knock my stepmom out of the running or even just fight her head on."

Conveniently enough, both Lilith and the Leviathan led organizations. And the Leviathan's had been created to take on the Bright Cross which could be tied to my stepmom.

"That shark was opposed to her from the very beginning. If I hadn't done it first, the Leviathan might have started a war. Had he prepared an organization that matched my stepmom's format so he could challenge her to chivalrous single-combat in the very end? Did he think she had declared war on him when the lowly Bright Cross attacked him?"

It was true my stepmom was taking on the world as a leader of Absolute Noah, but she was driven by a desire to ensure her precious family had a spot on the ark. She no longer had any interest in her authority and reputation as a demon, but the Leviathan's rivalry had still burned bright.

The Leviathan was the master of envy.

…It sounded silly, but this may have been the obvious conclusion.

"We finally have the whole picture."

I felt like we had gone around in a circle, but that meant the final diagram was quite simple.

Our enemy was the Leviathan.

Take care of that shark, and this would all be over.

I have no reason.

If I had to give one, I would simply say this is in my nature.