In the morning.
At Demon Slayer hideout.
The sky was stained in blood-red hues. Winds howled through the mountains like the cries of the dead.
A thick, unnatural pressure hung in the air—suffocating, malevolent.
A crowd had gathered—Hashira, Kakushi, and slayers, all standing still, frozen in silent dread.
"W-What is this?"
"Who… Who could've done this?"
At the heart of the hideout—etched into the earth with seared black flames—was a massive pentacle, burned into the very soil. Its shape pulsated faintly, like it was alive.
A heavy silence followed, until Ai Hanako stepped forward.
Her eyes widened, and her skin turned deathly pale.
She murmured, barely above a whisper, "They've found us…"
She turned to the others, heart pounding in her chest. "The Upper Moons… have reached our most sacred ground…"
Ai's breath trembled, her mind raced. "We're no longer safe. If this place is compromised, then nowhere is.
Was it X…? Or someone even stronger…?
Or… is this a warning? A curse? A game?"
"HANAKO-SAN!"
Chikafusa burst through the courtyard, his breathing ragged, his face slick with sweat.
Ai Hanako turned instantly. "Yamamoto-kun? What happened?"
His voice trembled. "We—we found something... Something far worse than before... You need to see this. Now."
No more words were exchanged.
She followed.
They sprinted through the corridors, through the east gate—towards the outer cliffs surrounding the hideout.
And then she saw it.
Her heart froze.
Ai stopped in her tracks, her eyes widened. Her hand shot up to cover her mouth.
"W-What… what is this…?"
Carved into the earth with unholy precision were six enormous symbols—each one a demonic mural, ancient and ritualistic, pulsing with an energy she couldn't comprehend.
At the northeastern cliff face—stood a grotesque drawing.
A large, muscular demon with short spiked hair, rage twisted into his features, and markings like clawed bandages stretched across his torso.
Dark lines coiled around the figure like restraints.
Chikafusa stepped forward, his eyes shaking. "Hanako-san… I know this demon."
She turned to him sharply. "W-What did you say?! You know this one?"
He nodded slowly, his voice filled with dread. "This… is Akaza. He was once Upper Moon 3. But now…
He's the current Upper Moon One."
"Y-You're serious…? This isn't a mistake, or some prank?!"
"A prank? Hanako-san, the blood used to paint these came from our own comrades. How could this be some twisted prank?"
Ai clenched her fists, pushing down the rising panic in her chest. She drew in a slow breath, steadying herself.
"Where… where are the other drawings?"
Chikafusa swallowed hard. "I'll show you."
Chikafusa leads her to the other side.
Ai followed, her heartbeat matching his pace.
They rounded a corner—
And stopped.
Etched into the southeastern slope of the cliff, a new figure loomed.
A tall, elegant demon with long parted hair, a black crown resting upon his brow, and two ornate fans in his hands. His eyes were drawn with unnatural beauty—sharp, smiling, soulless.
The image radiated cold.
Chikafusa stared, "This one… this has to be Douma. The Upper Moon 2," he said quietly. "Yushiro-san described him exactly like this."
Ai's gaze sharpened, her lips pressing into a thin line.
"Upper Moon 2…" she muttered. Her eyes burned with quiet rage. "He's the one who murdered Shinobu-sama's sisters…"
She clenched her fists. "I swear… I will destroy him. No matter what."
"There are even more," Chikafusa continues.
They moved again—This time towards the northwest slope.
Ai slowed.
And froze.
Her face drained of all color.
Drawn into the earth was a void-shaped entity, its form vague, shapeless, a mass of living shadow with jagged limbs. Its face was a smear of hollow eyes, and darkness seemed to spill from the sketch like real fog.
But what was worse—
Above it, sketched in unholy lines and archaic runes, was the figure of a horned, winged beast with a goat's face and massive wings spread like death itself.
A twisted symbol of Satan.
Ai took a shaky step back, sweat collecting on her brow.
"What… what the hell is this thing…?" she whispered.
"Is this even a demon…?"
Chikafusa stared at the drawing, a cold shiver ran down his spine.
"…Yushiro-san once told me… to never approach a shadow demon if I ever sensed one. Said it was something even he'd never seen… only heard about…"
He looked at Ai, eyes uneasy.
"I think… this could be the one. The demon they only whisper about."
Ai's throat tightened. "…Could this be X?"
She turned her head slowly, eyes still on the drawing. "Maybe Fuji-san knows something… but he never says a word."
Even after all they had seen, they moved forward.
To the southwest.
The wind had stilled. The air thickened.
And there—
Etched into the earth in hauntingly delicate lines—
A figure that didn't belong.
A girl.
Otherworldly. Divine. Unreachable.
She stood with six grand wings, feathers cascading like rivers of light. A halo hovered above her head, tilted faintly like a crown not meant to touch mortal air.
Her gown flowed endlessly, woven in strokes that shimmered like stardust.
And her face—
Serene. Innocent. Beautiful beyond words.
But unreadable.
They stopped in their tracks.
Chikafusa's voice dropped to a whisper.
"Is that… an angel?"
Ai couldn't answer.
They stared, as if any sound might disturb the holiness of the drawing. Yet something was wrong. Something they couldn't name.
Ai finally asked, "Yamamoto-kun… have you ever seen or heard of her?"
He slowly shook his head. "…No. Nothing. Not even a rumor."
She stepped closer, her violet eyes glinting —tracing every feature.
"There's no record of her in our archives. No memory. No mention from Yushiro-san… nothing from Fuji-san either."
Her voice grew tighter. "Not a single demon… looks like this."
She knelt down slightly, brushing her fingers just above the ground.
"…So why does this angel make my heart race more than the others?"
Chikafusa furrowed his brows. "…Could it be a trick?"
Ai's voice was distant.
"An angel among demons… or a demon wearing the skin of an angel. Who knows."
Then—they moved on.
South.
The atmosphere grew colder, the air heavier.
And then—
They saw it.
Drawn onto the scorched earth, etched in blood and ash, stood the image of a tall swordsman.
Hair long and flowing like midnight smoke, a katana clenched firmly in his hand. Power radiated from his stance.
But—
His eyes. Six of them.
Six cold, lifeless, horrifying eyes stared out from the drawing.
Ai felt her voice escape in a whisper. "…This one looks like a… Demon Slayer?"
Before she could finish—
Footsteps echoed. The crowd parted.
Oyakata-sama appeared, but not with his usual composure.
His face was pale. Haunted.
He stepped forward slowly. His lips moved, barely audible.
"Mi…chi…katsu…"
Ai turned, surprised. "Oyakata-sama… do you know this demon?"
A long silence.
Then, finally, his voice cracked and low.
"His name… is Michikatsu Tsugikuni. Once… the Moon Hashira during the Sengoku Era."
Ai blinked. "That name… I think I read about him in an old textbook… wasn't he…"
Oyakata-sama nodded gravely.
"The second strongest Demon Slayer in all of history. Only surpassed by one man—his brother. The creator of Sun Breathing."
Gasps rippled through the crowd.
Ai stepped closer to the drawing, eyes narrowed.
"Then… why is he here? Why does he have six eyes?"
The answer came, heavy and cold.
"Because," Oyakata-sama said,
"…he is a demon now."
Silence.
…
"WHAT?!" Ai's voice cracked, her expression breaking into disbelief. "What are you saying?!"
Oyakata-sama's eyes grew distant, as if recalling a wound too deep to speak of.
"You asked once why we've always lived in secrecy… why we built this hideout, protected by Kakushi, and covered our presence from the world."
Ai frowned. "I always thought… it was because of Muzan."
He shook his head, his voice gaining an edge of bitterness.
"No, it's not because of Muzan. It was because of him—
Michikatsu.
When he fell into darkness, he slaughtered my ancestor, the leader of the Demon Slayer Corps at that time…
And presented his severed head to Muzan like a trophy.
From that moment on… our legacy was hunted."
Ai's face paled, her fists clenched.
"How… how could a former Hashira do something like that?!"
Before anyone could respond, Chikafusa spoke up.
His voice was strained. "…Hanako-san. Oyakata-sama. Yushiro-san once told me something terrifying.
That this demon… Michikatsu… is even stronger than Muzan Kibutsuji himself."
The entire crowd froze.
Not a breath moved.
Ai swallowed, trembling. "…We already can't defeat Muzan together. If he's stronger than that monster…"
She didn't finish. No one needed her to.
Because they were all thinking the same thing.
And then—
North.
They reached the final figure.
It was drawn in writhing, chaotic lines.
A young man, face unsettlingly calm.
Curly hair, tentacles spiraling from his back, and razor-sharp eyes that seemed to burn right off the earth.
Chikafusa's voice was tight with hatred.
"That's him!"
He clenched his fists. "That's Muzan Kibutsuji!"
Ai's eyes narrowed, her voice low with fury. "So… the Demon King. The one who started all of this…
Thousands have died because of him. Suffered. Families are torn. Dreams crushed. One day, we'll definitely defeat him."
But even as she spoke with resolve—
A dark thought coiled in her mind.
She turned away from the drawings. "…But why?"
Her voice dropped.
"Why would X leave these here? Why would a monster like that… give us clues?"
She closed her eyes, thinking.
"Does he want us to understand… or fear?
Is he toying with us? Does he already know everything—where we go, what we think, who we trust?"
She stared up at the sky.
And then whispered to herself:
Are we fighting demons… or being played like pawns in their game?
And the wind began to howl again.
"He gave me these clues to confuse us. But in reality, these symbols or drawings make no sense to be here. I won't fall for his trap this time."
———————————————————————
Meanwhile,
In a silent, empty room.
The walls are ancient and cracked.
In the very center of the room, Jigen sat on the cold stone floor.
No furniture. No light. Just darkness.
His long obsidian-black hair draped over his pale hands as he wrote—
Page after page of complex, high-level mathematical equations.
The only sound—
Scratch. Scratch. Scratch.
His crimson eyes glowed faintly in the dark, staring deep into each line, calculating something that no human mind was meant to comprehend.
He wasn't solving math. He was measuring fate.
Suddenly—
Two delicate, glowing hands emerged from behind him, slowly wrapping around his chest.
"Are you done with your chores?" a soft, sweet voice.
Eliza.
She stepped into view, emerging from the shadows like a dream made of silk and starlight.
Her skin shimmered faintly, almost ethereal, glowing like moonlight on still water. Her skin is the finest silk, warm as the sun.
But Jigen didn't move. He didn't blink.
His fingers kept writing.
One final stroke. The equation ended with:
0
Then—
The pages ignited.
A soundless flame, black as night, crawled across the parchment. Everything burned to ash.
He spoke, voice low and cold.
"As I expected...
Everyone will die within six years. No exceptions. Not even Ren Hajime."
Eliza's hands slowly pulled back. She tilted her head.
A soft giggle.
"Still playing with futures and death tolls?
What do you think about our little display last night?"
Jigen finally stopped writing. But he didn't turn to her.
His voice was like a dead wind through a graveyard. "That's useless…"
The warmth in her expression faltered. "Useless?"
He continued, calmly—almost bored.
"Those drawings… As much as I now understand her—Even from the little data gathered yesterday—Ai Hanako will see through it. She'll realize they were only meant to confuse. To distract.
After Ren Hajime and Stone Hashira, I found her interesting…"
Eliza's eyes narrowed. "Stop saying her name in front of me."
A long silence followed.
Jigen finally spoke once more.
"The purpose wasn't deception. It was… a warning.
To show them their place. That they are playing against something far beyond them.
That their biggest threat is not Muzan…"
He paused.
Then whispered the name like it was a death sentence.
"…but Kokushibo."
Eliza stayed quiet. Her eyes reflected the flickering dark fire still dying on the floor.
Jigen's words sank deeper into the silence.
"And to remind them… that we could crush them anytime.
Even now."