The sounds of battle echoed from outside—within the smoky throne room, Marin looked suspiciously toward the source of the noise.

"What is happening?"

"Intruders. Didn't you girls bring them in?"

Setaguchi answered.

A tall man with a beard on his chin—his age is in his forties, but his appearance looks even younger than that.

With well-defined features, he is a teacher especially popular among guardians.

However, Marin had been acquainted with him since long before she entered Hikarinomiya Academy.

That was exactly why, when she heard from Suguro that Setaguchi was on the third floor, she decided to go see him first and foremost.

(Since there's an obvious landmark like a castle, it's natural that Erika would make a move. But—)

Marin had thought the people here were just ordinary humans.

But judging from these sounds, it seems a proper battle is taking place.

Have they been granted Kaigyo's power like Ooki and the others?

Or do they possess something else?

(...Investigate and bring the information back to Erika and the others.)

That's what she should do.

However, there was hesitation within Marin.

As if seeing through that, Setaguchi put his arm around Marin's shoulder.

Ruka glared at him intensely, but he paid her no mind.

"Don't make such a scary face. We're close, aren't we?"

"...I have no recollection of being intimate with you."

"How cold. We used to eat together a lot since you were little, didn't we? Just the three of us as a family."

Marin gently pushed his arm back and brushed it off.

Even so, Setaguchi smirked, seemingly convinced that Marin couldn't reject him.

"It's fine, Marin. You can even call me Papa."

"..."

"What's wrong? It's not a weird thing to say, right? Because we are—"

"Stop it! Don't touch me so familiarly!"

When Marin raised her voice, Setaguchi shrugged his shoulders and showed a teasing expression.

The two of them had been acquainted before Marin entered Hikarinomiya Academy.

In fact, since she was a baby.

"A rebellious phase, I wonder. But I heard you visited because you wanted to see me, yet you don't look like that at all. Marin, surely you aren't—trying to extract information from me?"

"What are you talking about."

"In addition, the young lady of the Hiyami Group is glaring at me like I'm her parent's murderer. I'd understand if it were affection, but I don't recall earning that much resentment."

"Don't worry about it. I've always had this kind of look in my eyes."

"Hah, do you think I can't tell if there's hostility or not? But you're a pitiful woman. I know you're in love with Marin. But your position as the young lady of the Hiyami Group and your gender won't allow it. No, that's wrong... the reason it's not allowed isn't that."

Setaguchi said, bringing his face close to Ruka this time.

"It's because you two are half-sisters, right."

She remains unfazed.

However, Marin couldn't hide her agitation.

"What are you saying...? Me and Ruka are half-sisters?"

"Because it's true, isn't it? When embedding a Fragment of Giraiguu into a fetus, genetic compatibility is important to maximize its benefits. That's why Marin's mother made a child with me."

"That's right. My mother did the same."

That act is not considered evil for believers of Kaisei kyou.

Naturally, Ruka's father was also aware of it.

However—Marin's father knew nothing.

"Wha... y-you knew...? That my father is the same as yours, Ruka... since before!"

"I found out after I fell in love with you."

"Kh...!?"

"I was happy. Because a red thread called blood connected me with the person I loved."

Drawing Setaguchi's blood is a stain.

However, she is proud from the bottom of her heart that she was able to become sisters with Marin.

That was Ruka's true feeling.

But Marin is still confused; she cannot straightforwardly accept that affection, which is so direct it even looks twisted.

"You're creeping me out."

Setaguchi said as if spitting it out.

"A man who forces his way into people's families is preaching morals now?"

"I'm just living according to the rules of Kaisei kyou. Therefore, I am right."

"Then why didn't you tell Marin's father about that? He probably still doesn't know. That his child is only the Kuragane Erika he abused so much."

"If he couldn't notice by looking at the difference between Marin and Erika, it just means he was a man of only that caliber. A normal human would realize by looking in the mirror. There's no way an excellent child like Marin could be born from his blood! It's exactly because she's of my blood. Ah, by the way, I've met that man. I happened to run into the three of you happily shopping together—hey, you remember, right Marin."

Marin says nothing, her eyes averted.

Then I'll tell it instead—Setaguchi recounts the events of that time, even though no one asked.

"Saying 'thank you for your support.' Your mother happily bowed her head. Influenced by that, that pathetic man bowed his head too. Marin understood, so you looked at me anxiously. That's right, the three of you weren't a family. The family was just me, your mother, and Marin. That man was left out in the cold in that situation, and do you know why? It's because he didn't bring Kuragane Erika along by his own will! If he had loved her as a daughter, the family might have been established! Hahaha, it's hilarious! Because he doesn't know, right? That I was the one who ordered him to raise Erika as a daughter suitable for a sacrifice!"

He looked truly amused.

That doesn't come from devotion to Giraiguu.

It is nothing other than Setaguchi Ataru's own sadistic nature making him do so.

"What's with that disgusted look, Marin. But you're the same; you obeyed me. You obeyed me and abused Kuragane Erika. Even though she was the only true, legitimate member of the Kuragane family, you continued to torment only her! At that point, Marin, you are inevitably my daughter. You're not Kuragane Marin, you're Setaguchi Marin!"

Setaguchi grabbed Marin's shoulders and rapidly poured out those words.

Marin's mother had an affair for a long time, making excuses saying "it's for Kaisei kyou."

Not just once or twice.

She had constantly, constantly continued to betray her husband.

And she gave birth to Setaguchi's child.

Thanks to the excuse, she felt absolutely no guilt, and proudly puffed out her chest saying "She's our child."

Marin's father didn't love his own child, making excuses saying "it's to keep peace in the family."

Just as his wife told him, he continued to pour affection only onto Marin, who wasn't his child.

Blindly believing that it was for the sake of the Kuragane family.

Not knowing that it was all to become a sacrifice for Kaisei kyou.

And Marin, making excuses saying "it can't be helped because I'm a child," grew up into the desired form.

Because she was excellent, she could do exactly as her parents told her since she was young.

So she grew up as told, and abused Erika as told.

Knowing that it was all Setaguchi's orders.

Knowing that her mother didn't love her father.

Knowing that their only true child was Erika.

Knowing it. Even though she knew it.

No, exactly because she knew—she was afraid that the current situation, which covered up everything, would be brought to light.

Harboring the foolish hope that if she just kept it sealed forever, this "distortion" wouldn't be found out by anyone.

In reality—if the world hadn't broken like this, everything probably would have ended in secret.

Erika would be killed as a sacrifice, and Marin would be splendidly raised as an executive of Kaisei kyou.

Everything exactly as Setaguchi planned, with no one (counted as a human) ending up unhappy.

"Please, Marin. Call me Papa. We're among the few family members left in this world; let's properly love each other."

Setaguchi hugs Marin, who is frozen with her eyes wide open.

Everything was a sound argument.

The Kuragane family, including Marin, had continued to make mistakes in everything.

While she despised her parents and hated Setaguchi in her heart, she had obeyed those words.

Just as desired, she grew into a perfect human being.

Is that not proof, more than anything else, that Marin is not the daughter of her father on the family register, but Setaguchi's daughter?

"Who am I?"

She had repeatedly searched for her identity, but—in the end, she might be nothing more than a believer of Kaisei kyou.

As her heart wavered like that—Gyges passed right beside Marin.

The fist pierced Setaguchi's face, blowing his body away.

At the sudden noise echoing in the throne room, the other teachers also looked at Ruka all at once.

"I'd appreciate it if you didn't touch my Marin so familiarly."

Both physically and mentally.

Ruka couldn't permit any further approach.

Then Setaguchi, slammed against the wall, stands up while lightly wiping his punched face.

"Hiyami... What's with that arm. That's not violence you should direct at your Papa."

"Strange. I hit you with the intent to kill, though."

"We, who have reached the True World, receive the favor of Giraiguu sama."

Setaguchi's arm was enveloped in a black liquid.

Even when he was punched by Gyges earlier, he had reflexively spat liquid from his mouth to guard.

"How is it? Are you envious?"

Setaguchi, showing off the part enveloped by Giraiguu, looks somewhat proud.

However, Marin, who is being held close by Ruka and in a state of mental exhaustion, shows no interest.

"I see, so you're not envious. Marin has always been like that; she doesn't try to believe as fervently as her mother. No, on the contrary, she despises it."

Marin, her mother, and Setaguchi.

There had been many occasions where the three of them sat around a table at a restaurant.

Her mother, showing the face of a woman.

Setaguchi, telling himself he was her father.

With no place to escape in such a place, Marin could only sip her orange juice through a straw, stare at the surface of the water in the glass, and avert her eyes.

"Even though she grew up as an excellent human resembling me just as her parent desired, she tries to convince herself 'I am different from my mother.' It's pitifully half-baked."

"Don't speak... like you know everything..."

"I do know. Because I'm your real father."

"Tch..."

"Perhaps you came here to settle your relationship with me, but—it's impossible for you. What can you do with a heart so full of hesitation?"

Everything is seen through.

Even if she won with power, with just that one word, Marin's heart crumbled to pieces.

Too weak.

To the point she hates herself.

"If there's a way, there's only one. Be defiant, and entrust yourself to Giraiguu sama. Acknowledge the correctness of your mother's choice. And realize that you are my daughter. Other than that, there's no way for Marin to establish her self."

"Could you stop disturbing Marin's heart with your delusions any further?"

"Don't interfere, Hiyami."

"That's my line."

"I can kill you, you know. Because in the True World, everyone is equal."

"You're acting tough; was there no human on the third floor who could handle Gyges (this power)? Rather—I wonder where the people other than the teachers went. There should have been many students too."

Just then, the doors to the throne room opened.

The two teachers who appeared were stained with blood and carrying a pole on their shoulders.

On that pole—human bodies, already slaughtered with their heads and internal organs removed, were skewered.

"Th-That is..."

Marin's voice trembles.

Ruka tightly squeezed her hand to encourage her.

"Heathens are not human—is it?"

"Wrong."

Setaguchi asserts confidently.

"We know they are humans. However, they did not accept the True World. Therefore, by taking them into our bodies, we feel faith together and purify the world."

Spouting incomprehensible logic without hesitation.

"The True World must be beautiful. Right?"

Without a shred of doubt that this is the truth of this world.

Words that seemed packed with the evils of Kaisei kyou, Ruka thought.

"You're making a face that says you don't understand. Are you guys 'enemies' after all? Then how did you reach here? When everywhere other than the True World should have perished long ago."

"Marin, words won't get through to these guys. It's useless to seek 'answers' from Setaguchi."

"Ruka... but."

"Marin!"

This time Ruka grabs Marin's shoulders with both hands, brings her face close, and declares.

"Your weakness is endearing. But I cannot endure a world where you break and disappear."

She deliberately uses such words, knowing that her words are mixed with a little conceit and cunning.

"Please give up. If you care for me even a little, Marin."

In essence, she's asking if Marin might have come to love her even a little by coming to this world.

If the time they spent alone together on the 2nd floor had drawn her heart closer.

It was a cowardly way of asking, predicated on such conceit.

Marin's eyes waver.

If Ruka—the person she loves—will be hurt by this, then she has no choice but to give up.

"...Ah, I see."

When Marin nodded, Ruka whispered "Thank you" and kissed her cheek.

"Beautiful friendship—no, affection?"

Setaguchi distorts his mouth, not hiding his irritation at failing to capture Marin.

Furthermore, his chest bulged, and he spat out black liquid.

"But... it's ugly. Compared to the whiteness of the True World, it's far too much!"

The liquid covers his entire body.

Ruka frowned.

"A terrible smell."

"It's as if he's rotting."

"In the end, they are just as blind as Ooki. Even though this place is not the True World."

"You can't see it because you don't love Giraiguu sama!"

Having completed his transformation, Setaguchi leaps at Ruka.

She reflexively tries to defend with Gyges, but blood spurts from her legs which she couldn't fully cover.

"Tch, fast."

"So he clad himself in Gangrene to increase his physical abilities. Ruka, let's escape from here!"

"I will destroy the wall!"

The other teachers in the throne room, clad entirely in black armor, were also about to attack the two.

Ruka punches a nearby wall, destroying it, and escapes through the opened hole.

But naturally, Setaguchi, who is superior in speed, gets around in front of them.

"Before God, humans are far too fragile!"

Countless eyes glared open on his head.

The moment lasers were about to be fired from them, Marin pushed Ruka down.

A beam of light grazes Ruka's shoulder.

With a jyuu sound, her clothes vanished, and her skin became a melted mess.

But this is no time for her movements to be dulled by pain.

"We're diving into that room!"

Marin opens a door with a tackle and slides into the room right in front of them along with Ruka.

"As if fleeing into a place like that will help youuuu!"

The lasers track the two.

However, an invisible wall blocked the attack.

"It's not working!?"

"Sanctuary... good thinking, Marin."

There is one place where a Sanctuary can be deployed.

But Erika and Marin are in different parties; Marin can deploy a Sanctuary on her own.

Realizing the lasers wouldn't pass through, Setaguchi tries to attack the two directly, but is repelled by the barrier.

"Why can't I pass. Why am I blocked. Marin, what is this power. What did you bring into this True World!"

"This place is not the True World. It is a world called the Adrasia Kingdom, destroyed by a monster called Kaigyo."

"You deny the True World!?"

"There is no such thing as Giraiguu. Setaguchi, the thing you guys summoned was a monster different from Giraiguu."

"Wrong! We know Giraiguu sama! We have interacted with Giraiguu sama! Look, this body is the greatest proof!"

Indeed, the black liquid covering Setaguchi and the others' bodies closely resembles the Fragment of Giraiguu Ooki and the others used.

Except for the fact that it emits a strong putrid stench.

"This power beyond human understanding—the kindness to share it. Who else but Giraiguu sama could do this? Have you looked up at the sky? You saw that giant figure, didn't you. He constantly watches over us from the heavens, and accepts us as brethren living happily in the True World. All of humanity must be grateful for that great heart! And if you committed an act of disrespect, you must rub your forehead against the ground and cry in apology! The presence or absence of faith doesn't matter! Before God, everyone prostrates equally; that is providence!"

Who would obey such logic preached at this point.

Marin and Ruka direct cold stares at him.

"Marin, if you accept him, Giraiguu sama will give you everything. Your hesitations too. And who you are too. Giraiguu sama will provide all the answers."

"That's... not an answer. Getting something like that is meaningless!"

"That's right Marin, there's no need to listen. You are the one who searches for the answer yourself, and above all, that man is not someone who brings answers. He's the root of all evil that breeds hesitation."

"Even though Marin and Ruka wouldn't exist if I weren't here?"

"So what? Because you can't love anyone, you cling to an evil god, and using faith as an excuse, you just lay your hands on every woman you can. And you always choose methods that make others unhappy!"

Even Ruka—it's not like she wasn't hurt when she found out.

She loved her parents.

Being believers of Kaisei kyou was a troublesome flaw, but she cared for her parents enough to actively participate in activities as a believer herself.

And yet, her father suddenly started saying he wasn't her real father.

Moreover, not looking sad or pained, but truly proud.

At that time, Ruka realized there was a fatal divide between herself and her parents.

Her kind, warm, beloved parents—she felt like they had instantly changed into completely different entities.

"Ah, I see. Pitiful children. You defy the path your parent has shown so clearly. You choose a path you know perfectly well is a mistake."

Just like Setaguchi right now.

The rooted values are simply far too different.

"If you go that far—you should meet him."

"Meet him?"

Marin tilts her head.

Setaguchi speaks proudly.

"As you know, Giraiguu sama responded to our faith and shared a part of His body with us. And now that the summoning succeeded and we have reached the True World, He has bestowed even further charity."

And he pointed to a ladder in the corner of the room the two were in.

"The answer is underground."

◆◆◆

Marin and Ruka descended the ladder.

A dark, long passageway continued ahead.

Not particularly because Setaguchi told them to, but because air was flowing from deeper inside, they thought they could escape from the castle.

"Does this underground passage really connect to the outside?"

"Since it's the castle where Queen Nemusia san lived, they must have prepared a path like this to escape."

"Then we should just go straight ahead, but—"

"But there's a weird sound coming from the side door. What do we do, take a look?"

The "Giraiguu" Setaguchi mentioned is probably inside here.

They didn't think it was the real Giraiguu; they considered it likely to be Kaigyo's Gangrene, which would be the Master of the floor.

Even to bring back information, they wanted to at least grasp its appearance and location.

When Marin nodded, Ruka placed her hand on the door.

"Ugh... terrible smell."

Marin frowns at the putrid stench overflowing from the opened gap.

It was a smell that seemed like an even denser version of that black liquid Setaguchi and the others wore.

And when they entered the room—

"Well now, something outrageous has appeared."

There, sitting imposingly, was an incredibly giant black slime filling the vast room.

Countless eyes were plastered on its surface, constantly moving restlessly, making it extremely creepy.

"Setaguchi and the others called that black liquid Giraiguu. Does that mean this is a part of Giraiguu?"

"But looking at that fang floating in the sky, didn't they call that Giraiguu too?"

"Do they not even grasp its appearance?"

"Because they're the kind of guys who call this place the True World; who knows how credible they are."

At least, it is confirmed that what is floating in the sky is Kaigyo's fang.

On the other hand, there is no doubt that the black liquid Ooki and Gii use is a part of Giraiguu.

Then, what is this monster that appeared before the two of them.

As they were observing, the entire room suddenly began to shake.

"What's happening...!?"

What appeared from the left and right sides of the room were giant human hands covered in scratches.

Furthermore, tearing open the ceiling, a giant human face also appeared.

"A giant... woman."

"She looks about our age."

The two ready their sword and fists, preparing for combat.

But strangely, they didn't feel hostility from that woman.

Though, a smile was constantly plastered on her face, making her extremely eerie.

Then, those giant hands began to move, pinching the black slime with their fingertips.

Tearing the epidermis with its nails, sinking its fingers inside, and forcefully pulling.

"Guuuuuuuh! U, Uuuuu, Guuuuuuuuuh!"

The slime let out a low groan.

"Is it... suffering?"

As Marin said, the slime looked like it was writhing in pain.

And the part grabbed by the giant finally tore off.

"Gugih, Guuuuuuuuuuh!"

An exceptionally loud scream echoed.

The woman threw the torn-off part in front of Marin and Ruka.

"Is this... for us?"

"Of course we have no intention of accepting it... right?"

"I wouldn't do something so foolish. As long as I have Ruka."

"I'm glad my love got across."

When Ruka said that jokingly, Marin's cheeks flushed red.

"Alright."

Ruka instinctively struck a gut pose.

"Why are you being festive."

"Because I felt a response unlike ever before."

"...Good grief, Ruka becomes an idiot when I'm involved."

"Because of love."

"I didn't feel any connection or anything... but I've always thought you were an attractive woman, Ruka."

Even while saying that, Marin looks more embarrassed than usual.

Perhaps because her heart is weakened by various things, Ruka's words and actions pierce her chest every time.

"For now, with this we know the Floor Master and its abilities to some extent."

"Yeah, we need to go back and formulate a plan."

Leaving the squishy writhing slime fragment in front of them, Marin and Ruka try to leave the room.

At that moment, a voice echoed in their heads.

『I won't forgive you.』

It was an inhuman voice, a mixture of voices of young and old, male and female.

They reflexively stop in their tracks.

"...Did you hear something just now?"

"What a coincidence, I did too."

They look back at the slime once again.

Then, words continuously flowed into their heads.

『I won't forgive you, I won't forgive you. Why do such a thing. Teaching me the taste of sweet honey. Asking for a price in return. Was that all to make me suffer?』

Anger, hatred.

Such emotions well up from inside their bodies, almost as if synchronizing with it.

『It hurts, it hurts, it hurts, stop it. Isn't it enough already. Haven't you fulfilled your grudge already. I didn't sip human lives because I liked it either! I merely sought it because it was given to me!』

It's not like they got angry along with it because of that, but—it seems that voice is not something as simple as "echoing in the head."

Much deeper.

Something mixed into the root of life is resonating, transmitting the voice to the two of them.

『I hate humans! Like I'll forgive you! Perish everything, be burned to nothingness by my light!』

In other words, genes.

Both Marin and Ruka had Fragments of Giraiguu embedded in their bodies before they were born, while they were fetuses.

If the reason they can hear the voice lies "there"—

"Ruka, don't tell me this guy is"

"I think it's exactly what you're thinking, Marin."

The black grotesque entity rotting, bound, carved, and continuing to suffer.

Looking up at it, Ruka declares its true identity.

"The main body of Giraiguu."