Kaen didn't sleep for two nights after the creature appeared in his room.
He sat by Yui's bedside, sword across his lap, eyes locked on every flicker of shadow. The wards glowed faintly across the walls — layers of sacred paper etched in blood and ash, whispering protective chants in low, hollow tones.
But none of it made him feel safer.
The crack in the mark on his chest had not closed. It throbbed now with every heartbeat, pulsing like something beneath his skin was trying to come through. He kept his robe buttoned tight, but the heat wouldn't go away. He wasn't sure if it ever would again.
Yui still hadn't woken up.
The slayer medics said her spirit had been touched — brushed by something from inside the door. Not a demon. Something older. Something that wasn't meant to exist.
Yoru stood at the entrance to the room that morning, watching Kaen in silence.
"You need rest," she said.
"I can't," Kaen replied. "What if it comes again?"
"It will."
He looked up sharply.
Yoru stepped inside, her arms folded beneath her cloak. "This wasn't a one-time event. That wasn't just a memory crawling through. It was a warning. The first. And the weakest."
Kaen's fingers dug into the hilt of his blade.
Yoru stared at him for a long moment.
"You need to understand something," she said. "We've had vessels before. People chosen to carry cursed things. Old bloodlines. Broken spirits. But none of them... none of them ever made it past the third stage."
Kaen's voice was quiet. "How many lived?"
"None."
He turned away.
"But you're different," she said. "That's why I haven't killed you."
Kaen's eyes snapped back to hers.
She wasn't smiling. There was no softness in her tone.
Just fact.
"Because if I thought you were just another cursed mistake… I'd have put a blade through your heart the moment I saw the mark."
Silence sat between them like a third person in the room.
"But you're still alive," Yoru said. "And you still have a choice."
Kaen looked at Yui again. "Not if it means leaving her behind."
"You don't have to leave her," she said. "But if you want to protect her… if you want to live long enough to become something more than a shell with a monster inside it... then you need to come with me."
Kaen stood slowly.
"Where?"
She turned to the door.
"To the mountains. To a place where that thing inside you won't be able to lie anymore."
They left that night.
Kaen didn't say goodbye to the other slayers. He only left a note with the medic watching over Yui: "Protect her like she's your own blood. If I come back different… don't let me near her."
He followed Yoru on foot, deep into the old mountain paths, where no torches burned and the wind howled like spirits tearing through bone.
The path grew steeper, colder, and the snow began to fall.
Ash mixed with it.
Even here — high above the village ruins, far from the outpost — the air still tasted of things long dead.
At the top of the trail, just beneath a jagged cliff, Yoru stopped.
Before them stood a gate made of black wood, untouched by rot or time. Talismans surrounded it in perfect rows. A single kanji burned across the door in red ink:
"Truth."
Kaen felt the mark on his chest pulse violently.
Yoru looked back at him.
"Once you step through… the demon will be pulled forward. You won't be able to silence it anymore."
Kaen said nothing.
She pushed the gate open.
Inside was a cavern — wide, hollow, and silent.
The floor was made of obsidian stone, carved with symbols Kaen couldn't read. In the center, a ring of burning candles circled a stone altar. Chains hung from the ceiling, clinking slightly in the cold air.
"Sit," Yoru said.
Kaen did.
"Don't resist what you see," she warned. "Let it come. Let it speak. But do not believe what it shows you."
Then she stepped back, her hand resting lightly on the hilt of her blade.
Kaen closed his eyes.
The mark burned like fire across his chest.
The world vanished.
He opened his eyes into darkness.
But not empty darkness.
There were walls. Made of ribs. Bones as tall as towers. Skulls cracked in half like ruined temples. And above him, a sky made entirely of red flame, flickering without heat.
Something was standing ahead.
A figure — tall, cloaked in shadow, with a crown of black horns curling backward.
Its face was hidden.
But Kaen knew it.
It was him.
No — it wore his shape.
The figure turned slowly, and when it spoke, its voice was his voice layered with hundreds more.
"So you finally came to meet me."
Kaen stepped forward, breath shaky.
"What are you?"
"I am what was sealed," it said. "I am what your ancestors buried in blood. I am what they passed to you when they let your family burn."
Kaen's fists clenched. "You're lying."
The figure smiled without a mouth.
"Am I?" it whispered. "Then ask yourself… why were you the only one left alive? Why did the demon choose you to enter?"
"I didn't choose this—"
"You were born for this."
The bones beneath Kaen's feet cracked.
"Your name is not a coincidence. Your blood is not clean. Your fire is not yours."
Kaen screamed and rushed forward, blade drawn.
He slashed at the figure — again and again — but it didn't move. The sword passed through it like mist.
"You cannot kill me," it said. "You are me."
Then the world collapsed inward.
Kaen fell through flame, through ribs, through screaming, whispering voices. His chest split open — not with pain, but with memory.
He saw a burning village — not Miboru, but older.
He saw a boy — a slayer — just like him.
And a mark on his chest.
And a voice inside.
The same voice.
Then everything went white.
Kaen woke gasping on the cold stone floor of the shrine. Sweat drenched his body. The mark on his chest was no longer a crack — it was a gap. A sliver.
A door… almost open.
Yoru stood over him, eyes wide.
"What did you see?"
Kaen didn't answer at first.
Then he looked up at her, voice quiet.
"I saw myself."
Far below, in the ancient hollows beneath the earth, a chained being opened one eye.
A single whisper left its mouth:
"He remembers."
The last of its chains snapped.