That night.
In the Butterfly Mansion.
The candlelight flickers across Ai Hanako's weary face.
Her desk is buried in books, but one lies open before her.
The one Jigen left.
Her eyes are bloodshot.
Dark circles bloom beneath them. Her hair clings to her face. She hasn't slept.
Her finger drags slowly across a page… Blood. Every line is written in blood.
————
Around 400 years ago.
Even before Yoriichi defeated Muzan Kibutsuji.
A forgotten place. Cold stone. A meeting drowned in silence and power.
Michikatsu Tsugikuni stands face-to-face with the Demon King. Muzan's presence crushes the air—an aura like molten fire.
Michikatsu's eyes are sharp, but his fists tremble.
"Kibutsuji Muzan…Will it truly make me strong? Immortal?"
His voice is low, uncertain.
Muzan smiles—slow, wicked. "Definitely! It will lift you from a pathetic human to an immortal demon. Even stronger than you could ever imagine."
He slices open his hand. Blood drips, thick and dark as ink.
"Drink this, Michikatsu. This is your fate. Your new life. Transcend this human life, become the first upper moon, the strongest demon after me."
Michikatsu kneels. The blood hovers before him like a curse…
He hesitates.
A flash—his wife, his sons, the life he walked away from without looking back.
Warmth… fading.
Then—he drinks.
Pain floods him. His muscles seize. His vision warps.
But he doesn't scream.
"To gain strength… I gave up everything."
Muzan smirks, "I've never tested my blood on demon slayer yet. It may take more time than turning a normal human into a demon. The stronger you are, the later you turn into a demon.
From now on, I hereby declare your new name… Kokushibo. "
3 days later.
The transformation is complete.
Kokushibo stands in the shadows outside the Demon Slayer Corps' stronghold. His six eyes glow, piercing the veil of dusk.
He takes a step forward. The air bends around him.
At the front gate, a handful of Demon Slayers spot the silhouette.
They prepare themselves. "There's a demon. Be ready!"
Swords unsheath. Breathings activate.
Then—
They see his face. The pattern. The uniform.
"Wait… the Moon Hashira?"
"…Michikatsu…?"
Confusion lingers for only a second.
Then—
He vanishes.
Slice.
Their heads are already falling.
No scream. No struggle. Only silence, and blood painting the stone.
Inside the Corps grounds.
A storm of death follows.
Slayers rush in—wave after wave—
But their swords shatter. Their lungs collapse before they can speak.
Limbs fall like leaves.
Kokushibo walks through them—graceful, silent, untouchable.
In the Ubuyashiki Mansion — Sengoku Era.
The Moon glows dimly above.
Inside, the head of the Ubuyashiki family sleeps soundly beside his wife and his children.
But outside—
Two Hashira stand vigilant.
The Snow Hashira and the Light Hashira step forward, eyes narrowing at the figure approaching in the dark.
"Michikatsu?"
"…What happened to your eyes?"
They see it.
The aura. The blade. The hunger.
"You're… a demon?!"
Kokushibo speaks—Low. Void. Absolute.
"There's no time for talking."
They launch forward—
A blinding burst of Light Breathing and a chilling wave of Snow Breathing colliding toward him.
Kokushibo raises his blade.
With effortless precision, he parries both strikes at once.
Then—
SWOOSH!
He unleashes a wave of crescent-shaped blades—
Their bodies hurled backward, arms severed mid-air.
Still, they stand. Bleeding. Burning. Shaking.
"Tch… We had no chance against the Moon Hashira before… but now…"
"He's not the man we knew… He's something else."
Too late.
In a flicker of movement—
He's already behind them.
Two perfect slashes.
Their heads fly. Their bodies collapse.
The gates to Ubuyashiki's home creak open as Kokushibo walks forward…
The silence is shattered.
Oyakata-Sama's wife jolts awake at the sound of the front doors breaking. Her vision blurry, half-lidded eyes adjusting—
Then she sees him.
Kokushibo.
A towering figure of dread. Six glowing eyes.
A blade that weeps blood. The air around him hums with malice.
She screams.
Oyakata-Sama wakes instantly. The children stir, their small faces turning in fear toward the door.
And there he stands.
Oyakata-Sama's voice is a whisper, trembling. "...Michikatsu… why…?"
Kokushibo steps forward, slow, steady. Each footfall echoes like death's countdown.
"I once bowed to this man. Now, I serve only the will of the demon king, Muzan Kibutsuji. His commands are absolute. Even if they lead me to Hell."
The children hide behind their mother, who steps forward—shielding them.
"If you want to kill our leader," she says, "Then you'll have to kill me first. I will not let you harm him alone."
Kokushibo's eyes shift—six of them, all void of warmth.
Then… for the first time…
Guilt.
"I left my wife, my children, because of my own selfishness… I wanted power, but forgot that power means nothing if you can't protect your loved ones…"
His hand tightens on the hilt of his katana—so hard his nails pierce his skin, blood dripping from his clenched fist.
But then—
His resolve returns.
"Sacrifice… is the cost of greatness."
He lifts his blade. No words.
Slash.
A single stroke.
Blood sprays.
Since that time,
The Demon Slayer hideout was relocated, hidden deep within the mountains.
The Kakushi Corps was born—to serve, to protect, to watch in the shadows. They would ensure this horror would never repeat.
Elsewhere.
In a decaying mansion veiled in ash and rot—
Muzan Kibutsuji sits cross-legged, awaiting tribute.
Before him, Kokushibo kneels.
In his bloodied hands—the severed head of Ubuyashiki.
Muzan smirks, "You've done a great job, Kokushibo. At last, my experiment was successful."
Kokushibo lifts his gaze, eyes calculating.
"This man seems overconfident… no wonder he is too powerful. But can he really defeat Yoriichi?"
Muzan's voice slices the air. "I can read your mind. Don't you dare compare me to some ordinary demon slayer!
I can still erase you from this existence."
Kokushibo stares at him for a bit, then lowers his head. "... I apologize, Muzan-Sama."
Years later.
Yoriichi Tsugikuni's blade cuts through destiny.
Muzan lies in ruins—body slashed into chaos, blood flooding the earth.
His form twitches, broken. His regeneration halts.
The wound glows red with the remnants of Sun Breathing.
Kokushibo appears in the aftermath.
He stares in disbelief.
Muzan—the Demon King—is trembling.
Eyes wide. Breath ragged. Like a child lost in the dark.
"Muzan-Sama… are you alright?" he asks quietly.
Muzan doesn't answer. He just shakes.
"Not even that man… could stop Yoriichi."
From that day forward—Muzan changed.
He fled. Hiding in layers of masks and names.
He formed the Twelve Kizuki, no longer trusting only himself.
His goal became survival first… and domination second.
The era of demons shifted.
And a legend—Yoriichi Tsugikuni—haunted them all.
—————
While reading the book,
Her finger slips. Her head droops.
Sleep, heavy and cold, wraps around her like a shroud. Her breathing slows—
She collapses into slumber on bloodstained pages.
.
..
…
She wakes.
But something is wrong.
The air is thick, rancid—choking her lungs.
The sky above is crimson, swirling like a dying flame.
The ground is black, like charred bones crushed into ash.
Ai blinks rapidly. Her heart pounds.
"Where… am I?" she murmurs.
She spins around—
No walls. No people. No sound.
Just that endless, empty plain under a bleeding sky.
Then—
A shriek!
A high-pitched, inhuman wail.
Ai flinches. Her breath catches in her throat. "Who's there?!"
No answer. Only silence.
Then—
The same scream again. Closer.
She grips her chest, trembling.
"A dream… This is just a nightmare. Isn't it? Should I… try to wake myself up?"
A long silence.
Then she straightens, eyes defiant.
"No. If this is a nightmare, I'll walk right through it. Whatever it is… I want to see it. This is not real after all."
She clenches her fists, steadying her breath, and begins to run towards the sound.
The ground crunches beneath her feet like bones. The air grows colder, denser.
The scream comes again—closer, louder—Raspy. Birdlike. But nothing like any bird of this world.
"It's getting clearer. I'm going the right way… I think."
At a distance…
A figure.
A young boy lying on the cold, dark ground—arms folded behind his head, legs crossed casually, as if this cursed world were nothing but a park.
His hair is long, dark, fading into a cyan hue at the tips. His robes are white, tattered, dusted in ash.
Beside him—an eerie, old katana, its edge faintly glowing.
Kasumi.
Ai Hanako approaches, cautious. "Hey… Are you alright? Where are your parents, kid?"
He opens one eye lazily, glancing up at her. Then shuts it again.
His voice is flat, calm, almost amused. "Another illusion huh?"
Her brows twitch.
She grabs his collar and lifts him halfway off the ground. "What do you mean?! You haven't clarified yourself yet! I am a real human!"
His eyes fluttered open. "Wait! Are you… a human?"
She releases him, "Do I look like a hallucination to you?"
He gets off her grip. "Seems like it's your first time. Are you also hunted by him?"
"Who?"
Kasumi's eyes finally meet hers—strangely sharp, unsettling.
"The faceless shadow. Crimson eyes. That thing."
Ai steps back slightly, heart skipping.
"Y-You've seen him too?"
He sighs.
"I've been stuck in these dreams for years. This is a dream number... 1,247."
"What?!"
"Every time I sleep… I die. Or worse. He toys with me like a cat with a mouse."
She looks at him, sympathy flashing across her face.
"I'm sorry you've suffered this much… but can't you just kill yourself to escape?"
Kasumi laughs softly. Cold.
"You think it's that easy? This isn't a dream anymore. It's a curse.
You don't decide when it ends—he does."
Ai's voice falters. "I… was planning to end it myself."
He looks at her solemnly. "Don't. Not unless you want your soul stuck here forever."
She inhales sharply. "Who is he? What's his name?"
Kasumi leans over, takes his sword, and carves a word into his forearm.
"Hey—stop!"
"Relax. Dream pain isn't real pain."
On his forearm, written in kanji—
J I G E N
He puts a finger to his lips.
"Don't say his name out loud. He hears it."
Her blood runs cold.
"How long will I be trapped in these nightmares?"
Kasumi looks away, expression grim.
"Until you kill him. Which means… forever."
She stays silent, then whispers,
"Can you tell me more about him?"
He nods.
"But don't ever repeat it to anyone. Not even in daylight."
He begins to tell her.
About Jigen. The walking shadow. The soul eater.
Her face turns pale as she listens.
"How do we kill something like that…?"
"You can't."
Silence lingers.
Then she speaks again.
"I want to ask about another one. Another demon. But she's… different."
"Go ahead."
"A girl. Beautiful beyond words. Like a goddess. But perhaps a demon. I don't know her name…"
Kasumi narrows his eyes slightly. "You mean Eliza."
Ai's heart skips. "You know her?"
He nods.
"Upper Moon Four. A divine creature wearing demonic skin. An angel with blood on her hands."
She gulps. "Is she like him?"
"No. She'll talk to you. Maybe even help you…
But be careful. She doesn't need to harm you to ruin you."
"Why?"
"Because she's beautiful enough to make you forget your mission.
And once that happens… you're already lost."
He explains everything about Eliza to her.
She nods slowly. "I understand."
Then extends her hand toward him.
"I should've introduced myself sooner.
My name is Ai Hanako. It's a pleasure to meet you."
Kasumi tilts his head thoughtfully, tapping his chin with a faint smirk.
"I am Kasumi Matsunaga—"
Suddenly, his eyes shoot wide open.
"Wait a second—Ai Hanako?! The Flower Hashira?"
She arches a brow, her tone suddenly cautious. "That's correct… But how do you know me? You're not with the Corps."
Kasumi leans forward.
"When you were nearly killed by Upper Moon 5… Do you remember who fought him and saved you all?"
Ai stiffens, her breath catching.
"You… were there? Who saved us?"
He grins, a rare spark of pride in his voice. "That was me. I'm the one who defeated him."
Ai blinks.
Then places her palm gently on his forehead.
"Hmm. No fever. You're talking nonsense just fine."
He brushes her hand off, unamused.
"Then how would I know so much about that fight? Every move. Every wound. Every scream?"
Her smirk fades. She studies him a moment longer—then gently pats his shoulder.
"Either way… you saved my life. So I owe you a thank-you."
She eyes him again, more curious now. "But if you're not a demon slayer… who are you really?"
His expression softens, strangely poetic.
"Just a wanderer… who kills demons without a uniform or rank. I walk the path they abandoned."
Ai lets out a soft laugh.
"You really talk like some ancient warrior monk, you know that?
You're stronger than most of us Hashira. So tell me— who taught you?"
A strange, tender light shines in his eyes—like the mere mention of that person fills him with meaning.
"My master… is Ren Hajime."
Silence.
Her smile disappears. Her lips part in disbelief.
"R-Ren Hajime… is your master?"
He nods solemnly. "Hajime-San told me about you. He said you were… different. Special."
Her breath shakes slightly, but she smiles—genuine, warm, layered with something deeper.
"So he was real… Where is he now—?"
Suddenly—
A blood-curdling scream slices through the air, shrill and distorted.
She flinches hard.
"W-What was that?!"
Kasumi stands. "Come. I'll show you."
They begin moving through the misty landscape.
The air thickens—pressure rising with every step, as if the world itself were recoiling in fear.
Then—
They arrive.
And Ai's eyes widen in awe and terror.
In the surreal crimson twilight, under a cursed sky:
Five colossal beasts clash violently against a single faceless doll.
—A monstrous alpha wolf with six glowing eyes.
—A white phoenix with blazing blue eyes.
—A komodo dragon, enormous and scaled like frozen sapphire.
—A fox, golden and majestic, with multicolored, shifting eyes.
—And a gigantic, shadow-drenched raven with blood-crimson irises.
Together, they are locked in a savage, chaotic war—
All against one solitary figure.
A blank, faceless doll wearing Ren Hajime's outfit.
Each impact of their clash shakes the world itself. The ground quakes. The sky seems to tear.
She gasps under her breath.
"Hajime-kun… he's fighting them all? The Upper Moons… and Michikatsu?"
Kasumi glances sideways. "You even know about Michikatsu? Huh. That's rare for a slayer."
Her hand instinctively reaches for her katana.
But Kasumi's hand stops her, firm on the hilt.
"Wait. Don't. You'll be obliterated before you even blink. These aren't just demons. They're monsters built from fear itself."
Her eyes burn with fury.
"I don't care. I failed to protect Hajime-kun once. I won't make the same mistake again."
In a flash—
She unsheathes her katana and lunges toward the battlefield.
"Hajime-kun!! I'm coming—!"
But before her blade could even rise—
SHHHHKK!
The cursed raven swoops down, its obsidian wing slicing toward her throat like a guillotine.
In that blink of death—
Kasumi blurs through the air, catching her mid-fall, barely avoiding the fatal blow.
"Are you crazy?! I've tried saving Hajime-san hundreds of times in these dreams. And every time—I die. We're not strong enough. Not yet."
Ai stares at the monsters—jaw trembling, pupils shrinking.
Then—
A blur of motion behind them.
Ren Hajime moves like lightning, his blade already mid-swing.
SHIIING—!!
The blue komodo dragon and blonde fox are split open in perfect arcs.
Without slowing down—
Ren turns, his crimson blade slicing through the wolf's leg and the raven's wing, crashing them both to the ground in roars of agony.
Ai gasps. "Hajime-kun…"
But the moment his blade aims at the final beast—the white phoenix.
The wounded raven screeches and dives in, shielding her with its ruined body.
CLANG!
Ren's katana cleaves through the raven's beak—its defense shattering—
But the wolf launches, tackling Ren like a meteor, hurling him across the crimson plains.
Ren skids midair, lands cleanly—barefoot, silent.
The phoenix's crystal-blue eyes glow radiantly.
Kasumi growls.
"That phoenix... it's healing them!"
They charge—
Both Ai and Kasumi strike at the phoenix from opposite sides, blades flashing—
But the phoenix—
WHOOOOM!
Unfurls its wings and blows them away like rag dolls.
CRASH!
Both smash into the dirt—but immediately push up, blood in their mouths, defiance in their eyes.
Then—
In a flash of blue light—
The phoenix appears right in front of them.
Its glowing azure eyes bore down like divine judgement.
Its claws rise—mere inches from their exposed throats.
Death is certain.
"Wait!" Kasumi yells.
Everything freezes.
The phoenix pauses mid-air. Then slowly lowers to the ground—towering three times their height.
Its head tilts slightly… curious.
Kasumi breathes heavily. "We're not here to fight. Do you even know when this dream ends?"
The phoenix blinks.
Then tilts its head again—almost… puzzled.
Ai steps forward, her voice softer now. "She's not like the others… She feels gentle."
She slowly raises her hand to caress the phoenix's feathers—
But the phoenix pulls back, lifting its head high, regal and distant.
Kasumi says.
"Yeah… Eliza doesn't like being touched. Elegant as a goddess. Proud as a queen."
Another scream—
Shriller. Sharper.
The phoenix lifts its wings and bolts toward the battlefield like a streak of white flame.
Kasumi and Ai follow, blades drawn, hearts racing.
They reach the edge of the broken dreamscape—
And freeze.
Ren's doll stands bloodied, motionless, surrounded by the torn remains of the wolf, the fox, the komodo, and the raven.
The battlefield is drenched in their black blood, smoke rising from the cursed ground.
But none of them move.
No second wind. No tricks. They're dead.
Yet the phoenix doesn't attack.
It lands beside the fallen raven, wings trembling, letting out a low, almost grieving cry.
Ren's doll watches. Silent. Sword lowered.
Ai whispers, confused. "Why aren't they fighting anymore…?"
The phoenix's crystal-blue eyes begin to glow. It stretches its wings to the heavens—
But nothing happens.
No light. No healing. Only silence.
Kasumi narrows his eyes. A bitter smile on his lips.
"Glad to see even the Upper Moons… can feel pain. It's the best time to finish them."
He grips his katana and steps forward.
Ai's voice trembles, hesitant. "But… in this state? She's not even fighting back…"
"They're demons after all, especially the upper moons. They all deserve to die."
The phoenix desperately nudges the raven one last time—
But it doesn't move. Its eyes are lifeless.
Kasumi breathes deeply. Cold resolve in his gaze.
Then—
SLASH!
The phoenix's head drops, gently, like a falling petal.
The dream begins to collapse.
The world shatters into stardust—
One by one, the beasts vanish. The crimson sky fades.
Even Ren's doll disintegrates into thin air.
Ai stares in disbelief.
"Is it… over?"
Kasumi lowers his blade, his hands shaking slightly.
"It's real… We're finally free… from his curse."
He turns to her, a smile breaking through his exhaustion.
"Hanako-san… I failed for a thousand nights… but in your first—you ended it. You're… amazing."
His form begins to dissolve, fragmenting into mist and gold.
"Thank you… I'll remember this.
We'll meet again. Very soon…"
And then—Darkness.
…
She bolts upright—awake.
The world is real again.
The morning sun filters through the Butterfly Mansion's windows.
Ai sits there, breath ragged, her hands trembling. "I've… been asleep for hours…"
She looks down—The book is gone.
"Wait—what? Where is it?!"
She frantically checks the desk, the drawers—nothing.
"I didn't even finish half of it…"
Then she stops.
A sudden thought strucks her mind. "Was that dream… Hajime-Kun… Matsunaga-Kun… Upper Moons… White Phoenix… all of it… was real?"
She walks to the window, bathed in dawn's first light.
"It was real… I know it was.
Muzan… Jigen… Michikatsu…
I'll fight. No matter what. Even if I stand alone. I will not give up.
Not until the last breath leaves my body."