Screen 1 – The Descent Into Chaos
(Sans and Papyrus Reaction Only)
The moment Muzan activates the spell, the ground beneath everyone shatters like glass.
The sky flips.
Floors stretch upward.
Walls twist sideways.
Gravity breaks completely.
Tanjiro, Hashira, and slayers vanish into the darkness—
But we focus on Sans and Papyrus.
---
Sans's Reaction
Sans feels the world tilt for half a second.
The air distorts.
The horizon bends.
And then—
WHOOSH—!!
He and Papyrus fall into a spiraling void.
Sans doesn't scream.
He just sighs, eye flickering.
"yeah… figures.
the final battle couldn't start normally."
He twists mid-air and lands on a floating stone platform with a soft thud.
He stuffs his hands into his pockets.
"infinity castle, huh?
weird place.
creepy architecture."
He looks around the endless halls stacking on top of each other.
"muzan's definitely compensating for something."
---
Papyrus's Reaction
Papyrus, meanwhile, falls while yelling dramatically:
"BROTHER!!
WHY IS THE FLOOR FLYING AWAY FROM US!?!"
He spins like a windmill.
"I DID NOT SIGN UP FOR VERTICAL HALLWAYS!"
Sans teleports and catches him before he hits a shifting staircase.
Papyrus lands, staggering.
"WH-WHAT IS THIS PLACE!?"
He stares at the endless corridors, upside-down rooms, and floating doorways.
Paintings blink.
Floors move.
Doors breathe.
Papyrus grips his spear tightly.
"IS THIS SOME KIND OF MEGA, ULTRA, EXTRA EVIL MAZE!?"
Sans nods.
"pretty much."
Papyrus looks around nervously.
"SO MANY STAIRS…
SO MANY CEILINGS…
AND WHY ARE THE CEILINGS ALSO STAIRS!?"
Sans pats his shoulder.
"welcome to the infinity castle, bro."
Papyrus straightens up, trying to look brave.
"OKAY THEN!
IF THIS IS THE FINAL DUNGEON…
THE GREAT PAPYRUS SHALL CLEAR IT WITH HONOR!"
He takes one step—
The floor moves sideways like an escalator.
Papyrus screams again.
"BROTHER THIS CASTLE IS CHEATING!!"
Sans smirks.
"told you.
this is gonna be one heck of a level."
The two skeleton brothers stand ready, alone in the shifting maze—
The final war against Muzan has begun.
Screen 2 – War of the Hashira
The Infinity Castle stretches forever—
floating rooms, falling staircases, endless tatami floors twisting in impossible angles.
Every Demon Slayer is ripped away into a different part of the dimension.
Screams echo.
Drums shake the walls.
The war has officially split into dozens of battlefields.
---
The Hashira Are Pulled Into Their Fights
Giyu slides across a falling hallway and lands in a frozen chamber.
Sanemi crashes into a rooftop room full of wind and white mist.
Muichiro appears in a narrow wooden corridor filled with shifting walls.
Gyomei stands inside a stone chamber that feels like a shrine.
Obanai lands in the center of a room lit only by candles.
Mitsuri crashes through a bright twisting hall exploding with force.
Each Hashira can feel it:
An Upper Moon is waiting for them.
This is a battle to the death.
---
Sans Chooses His Path
Sans watches the rooms move like puzzle pieces.
One staircase collapses beneath him.
Another door opens by itself.
He senses two familiar auras—
Tanjiro's breath
and
Giyu's calm water rhythm.
Sans sighs.
"guess that's my cue."
He turns to Papyrus.
"i'm going to find tanjiro and giyu.
they're gonna need backup."
Papyrus salutes instantly.
"OF COURSE, BROTHER!
GO HELP THEM!
THE GREAT PAPYRUS SHALL HOLD HIS OWN!"
Sans raises an eyebrow.
"you sure?"
Papyrus nods proudly.
"I WILL FIND MY OWN PATH AND ASSIST ANY SLAYER IN NEED!
I AM NOT AFRAID OF WEIRD FLOATING HALLWAYS!"
The floor beneath him rotates.
Papyrus falls sideways.
"OKAY I AM A LITTLE AFRAID—
BUT I WILL STILL FIGHT!"
Sans chuckles.
"be careful, bro."
Papyrus points his spear dramatically toward the twisting horizon.
"YOU TOO, SANS!
SAVE TANJIRO!
AND DON'T LET THE FANCY WATER HASHIRA DIE!"
Sans turns and steps through a shifting doorway—
And disappears into Giyu's battlefield.
---
The War Splits Completely
Papyrus lands in a glowing chamber and takes a battle stance.
"COME AT ME, EVIL DEMONS!
THE GREAT PAPYRUS…
IS READY!"
Meanwhile—
Tanjiro struggles through rotating halls trying to reach Muzan.
Giyu stands alone as a shadow steps out to face him.
Sans appears beside him, eye glowing faintly.
"hey.
mind if i join?"
Giyu nods once.
"Stay close."
The war of the Hashira has begun.
Screen 3 – Akaza vs Giyu, Tanjiro, and Sans
A massive chamber inside the Infinity Castle suddenly stabilizes.
The walls stop shifting.
The floor settles into a wide arena.
And from the darkness—
A familiar figure steps out.
Blue markings.
Calm expression.
Deadly aura.
Akaza. Upper Rank Three.
Tanjiro freezes for a moment.
His fists clench.
"Rengoku…
I won't let him fall for nothing."
Giyu draws his blade silently.
Sans appears beside them, eye glowing blue.
"looks like round two."
Akaza smiles peacefully.
"You again…
The water Hashira.
The boy with the mark.
And… the skeleton.
Good.
Give me a fight worthy of growth."
---
The Fight Begins
Akaza launches forward.
His fist creates a shockwave that shatters the floor.
Giyu blocks with Water Breathing, Tenth Form – Constant Flux.
Tanjiro darts in with Sun Breathing, Fourth Form – Burning Bones.
Sans teleports behind Akaza and fires a Gaster Blaster that forces him to turn.
Akaza grins.
"What wonderful teamwork."
His "Destructive Death" techniques explode around them:
Air Type
Leg Type
Annihilation Type
Each strike shakes the castle.
Giyu's movements grow sharper.
Tanjiro's blade burns brighter.
Sans mixes gravity pulses with perfectly timed teleports, forcing Akaza to reposition again and again.
But the Upper Rank's regeneration and instincts stay overwhelming.
---
Akaza Focuses on Tanjiro
Akaza locks eyes with Tanjiro.
"You…
You carry the spirit of someone who refuses to break.
Show me more."
Tanjiro charges, shouting:
"You took Rengoku from us!
I won't run away again!"
The two clash in a swirling storm of Sun Breathing and martial strikes.
Sans teleports in and uses gravity to slow Akaza's next punch.
Giyu slices down the opening with Water Breathing, Eleventh Form – Dead Calm.
For the first time, Akaza steps back.
"Impressive."
---
Akaza's Memories Awaken
As the battle drags on, something in Akaza begins to change.
A faint memory.
A voice calling his name.
Snow falling.
A promise made long ago.
He hesitates.
Tanjiro sees it.
"You're… remembering."
Akaza clutches his head.
"No…
I… don't need… humans…"
But the memories hit harder.
His fiancée.
His master.
His past life filled with love instead of loneliness.
Giyu stops attacking.
Sans lowers his blaster.
Tanjiro speaks quietly.
"You weren't born a demon.
You were forced to become one.
You don't have to keep fighting."
Akaza finally looks peaceful.
His eyes soften.
"So…
this is what it feels like."
His body begins to fade.
He doesn't resist.
He accepts the end Rengoku wanted for him.
Akaza smiles gently.
"This…
is peace…"
He dissolves into dust, releasing himself from Muzan's control.
Tanjiro bows his head.
Giyu closes his eyes.
Sans sighs quietly.
"finally… he gets to rest."
The chamber falls silent.
Upper Rank Three is gone.
Screen 4 – Papyrus, Kanao, and Inosuke Arrive Together
Papyrus wanders through the shifting maze of the Infinity Castle, spear raised high.
Every hallway twists.
Floors move like conveyor belts.
Doors slide in and out of the walls.
Papyrus shouts confidently:
"COME OUT, EVIL DEMONS!
THE GREAT PAPYRUS IS READY TO FACE YOU!"
A sudden crash echoes from above.
Papyrus looks up.
"WHAT WAS THA—"
BAM—!!
Inosuke crashes through the ceiling and lands on Papyrus like a bowling ball.
Papyrus flails.
"AAAAAUGH! GET OFF MY RIBS!!"
Inosuke jumps up, slamming his swords together.
"YAAAH! THIS PLACE IS AWESOME!
FLOATING ROOMS!
MOVING FLOORS!
IT'S LIKE A DEMON'S PLAYGROUND!"
Papyrus huffs, brushing dust off his armor.
"YOU NEARLY BROKE MY MAGNIFICENT BONES!!"
Inosuke points at him with excitement.
"SKULL MAN!
YOU'RE FAST!
WE SHOULD FIGHT SOMETHING RIGHT NOW!"
Papyrus sighs.
"CAN WE AT LEAST FORM A TEAM FIRST!?"
---
Kanao Appears
A soft tapping sound echoes from a side corridor.
Papyrus and Inosuke turn.
Kanao steps out of the shadows, calm and focused, butterfly pin glowing faintly.
She bows lightly.
"I'm glad to see allies…
This place is dangerous."
Papyrus beams.
"KANAO! YOU SURVIVED THE FALLING FLOORS! WONDERFUL!"
Inosuke stares at her.
"HEY!
SMALL QUIET GIRL!
WANNA FIGHT DEMONS WITH US?!"
Kanao's eyes shift between the two of them.
She looks confused… but determined.
"Yes.
We should stick together.
This castle keeps pulling everyone apart."
Papyrus nods dramatically.
"THEN I, THE GREAT PAPYRUS, DECLARE THIS A NEW SQUAD!"
Inosuke pumps his fists.
"YEAH!
TEAM… UH…
TEAM LOUD NOISES!"
Papyrus gasps.
"THAT NAME IS TERRIBLE!"
Kanao smiles very slightly.
Papyrus quickly raises his spear.
"OUR GOAL IS CLEAR!
WE FIND TANJIRO…
AND WE SMASH ANY DEMONS IN OUR WAY!"
Inosuke roars.
"LET'S GO!"
Kanao tightens her grip on her sword.
Papyrus leads the charge down the twisting hallway—
and the castle shifts again, opening a new battlefield beneath them.
Screen 5 – Doma vs Kanao, Inosuke, and Papyrus
The Infinity Castle suddenly freezes into a cold, silent hall.
Frost spreads across the floor, and the air turns icy.
Kanao, Inosuke, and Papyrus step inside together.
At the center…
sits Douma, Upper Rank Two.
He smiles with a calm, empty expression.
"Oh?
More guests?
How wonderful."
Papyrus raises his spear.
"YOUR SMILE IS VERY CREEPY!!
PLEASE STOP SMILING LIKE THAT!!"
Inosuke charges immediately.
"KANAO! SKULL MAN! LET'S TAKE HIM DOWN!"
Kanao stays still—
watching Douma carefully.
She senses something different.
He is slower.
Weaker.
His movements are not as smooth as they should be.
Then she realizes why.
---
Shinobu's Plan Starts Working
Kanao whispers:
"Shinobu…
Your plan worked."
Shinobu's poison, which she had prepared specifically for Douma, spreads inside him.
His body begins to fail from the inside—
not with gore, but with clear weakness.
His strikes lose force.
His balance slips.
His calm expression cracks.
Douma tries to laugh it off.
"Oh dear… I don't feel quite… right."
Papyrus points proudly.
"THAT'S BECAUSE YOU MESSED WITH THE WRONG HASHIRA!"
---
Kanao and Inosuke Attack Together
Inosuke dashes in with wild movements, forcing Douma to defend.
Kanao slips through the opening with perfect timing, each step silent and sharp.
Douma tries to counter—
but he's too slow now.
The poison is eating away at his strength.
Kanao's eyes harden.
"This is for our master…
and for my sister."
Inosuke roars beside her:
"LET'S FINISH THIS!"
Papyrus jumps in front of them, blocking falling ice shards with enormous bone barriers.
"FEAR NOT!
THE GREAT PAPYRUS WILL COVER YOU!!"
---
The Final Strike
Douma stumbles—
his legs finally giving out.
Kanao steps forward.
Her hands steady.
Her breathing calm.
Her heart clear.
She sees Shinobu's smile in her mind.
She lifts her blade.
"Rest now, Shinobu."
With one final, precise attack, Kanao finishes the fight.
Douma's cold body stops moving.
His expression empties completely.
The chamber falls quiet.
---
Aftermath
Inosuke punches the air.
"WE WON! WE WON! UPPER RANK TWO IS DOWN!"
Papyrus claps loudly.
"KANAO! YOU WERE AMAZING!
YOU FOUGHT WITH HONOR AND STYLE!"
Kanao lowers her head, tears gathering at the corner of her eyes.
"Shinobu…
you can finally be free."
For the first time, she allows herself to cry—
softly, quietly, holding her blade close.
Papyrus rests a comforting hand on her shoulder.
"WE'RE HERE, KANAO.
YOU'RE NOT ALONE."
The battle with Douma ends.
Screen 5 – Zenitsu vs Kaigaku
Inside the Infinity Castle, lightning cracks across a long wooden bridge.
Zenitsu steps forward, breathing steady, eyes sharp even though he's unconscious.
Across from him stands Kaigaku, now an Upper Rank, electricity crawling across his skin.
Kaigaku smirks.
"You were always weak, Zenitsu.
Always crying.
Always behind me."
Zenitsu doesn't answer.
He simply lowers his stance.
Silent.
Focused.
Calm.
Kaigaku grows irritated.
"Don't ignore me!"
He fires a blast of demonic lightning down the bridge.
CRACK—!!
Zenitsu moves.
---
Zenitsu Unleashes His Growth
He rushes forward at impossible speed, faster than Kaigaku can track.
Kaigaku shouts:
"YOU KNOW ONE MOVE!
YOU CAN'T BEAT ME!"
Zenitsu whispers quietly:
"That's why I created a new one."
Kaigaku freezes.
Zenitsu's aura shifts—
fierce, angry, determined.
Seventh Form: Flaming Thunder God.
Zenitsu strikes—
his entire body flashing like a falling star.
SHOOOM—!!
Kaigaku can't counter.
Can't dodge.
Can't scream.
The battle ends in a single, clean motion.
Zenitsu lands behind him, sword lowered.
Kaigaku collapses.
Zenitsu finally speaks, voice trembling.
"Master…
I told you I would grow stronger."
---
Sans and Papyrus Reaction (Small Scene)
In a nearby corridor, Sans and Papyrus feel the shockwave.
Papyrus jumps.
"WHAT WAS THAT LIGHTNING!?
DID ZE–ZE–ZENITSU EXPLODE!?"
Sans squints down the hallway.
"nah.
that's his new trick.
kid's leveling up."
Small demons rush them—weak ones drawn by the noise.
Papyrus twirls his spear.
"LEAVE THIS TO ME, BROTHER!"
He charges and knocks the demons back with bone platforms and light strikes.
Sans fires a small blaster to finish the rest.
"okay.
let's go check on blondie."
---
Zenitsu Stands Victorious
Sans and Papyrus reach the bridge just as the fight ends.
Zenitsu is shaking but standing.
Papyrus cheers loudly.
"ZENITSU! YOU WON!!
YOU BEAT THE LIGHTNING DEMON ALL BY YOURSELF!"
Sans nods.
"nice work.
guess you're not scared anymore, huh?"
Zenitsu wipes his eyes.
"I'm always scared…
But this time…
I didn't run."
Papyrus hugs him so hard Zenitsu squeaks.
The trio stand together, ready for the next battle
Screen 6 – Nakime vs Obanai and Mitsuri
(Canon Fight, Sans and Papyrus Reaction Only)
The Infinity Castle shifts violently.
Rooms stretch.
Floors rise like pillars.
Whole hallways collapse and rebuild in seconds.
At the center of the chaos sits Nakime, the Biwa Demon.
Her fingers tap the biwa strings calmly.
Every time she plays a note—
TONN…
The castle reshapes instantly.
Obanai slashes forward.
"Stop running."
Nakime plucks the strings again.
The entire room flips sideways.
Walls turn into ceilings.
Ceilings become bridges.
Obanai lands upside down, gripping the floor with his claws.
Mitsuri charges in, smiling through the pressure.
"This is so dizzy!
But we can do this!"
Nakime watches silently, unemotional.
She plays again.
Dozens of rooms collapse into one giant chamber, crushing everything except Obanai and Mitsuri.
But the two Hashira push through.
Obanai dodges every trick, weaving through the shifting shadows.
Mitsuri smashes falling walls with raw strength.
Nakime tries to teleport them endlessly, but the Hashira refuse to let her escape.
Obanai gets close—
Mitsuri breaks through another wall—
and with perfect timing, Obanai finishes the fight.
Nakime's form dissolves.
The Infinity Castle trembles as control slips away.
The demon is gone.
The maze begins collapsing.
---
Sans and Papyrus Reaction (Short)
Far away in another corridor, Sans feels the entire castle shake.
He pauses.
"welp.
someone just took out the teleporting demon."
Papyrus loses balance as the floor tilts.
"THE WHOLE CASTLE IS WIGGLING!!
WHO DEFEATED THE MAZE DEMON?!"
Sans shrugs.
"my guess?
snake guy and muscle girl."
Papyrus gasps.
"THEY'RE AMAZING!"
Sans nods.
"yeah.
and we're running out of time."
The castle continues to collapse, pulling everyone closer to Muzan.
Screen 7 – Kokushibo vs Sanemi, Muichiro, Gyomei, Genya
(Sans and Papyrus arrive after the battle – sad reaction only)
The Infinity Castle falls silent as four Demon Slayers stand before the strongest Upper Rank of all.
A tall figure with long black hair.
Six eyes.
Moon-shaped blades glowing on his sword.
Kokushibo – Upper Rank One.
Sanemi grits his teeth.
Muichiro steadies his breathing.
Gyomei raises his flail.
Genya loads his gun with shaking hands.
Kokushibo speaks softly:
"You have no chance.
But you may try."
The fight begins like a storm.
---
The Battle (Safe Summary)
• Kokushibo moves faster than sound
• Gyomei's strength shakes the entire castle
• Sanemi pushes forward harder than anyone
• Muichiro awakens his mark and strikes with everything he has
• Genya keeps firing to support them
But Kokushibo is overwhelming.
He breaks the battlefield apart piece by piece.
Muichiro's strikes weaken.
Genya collapses.
Gyomei falls after his final attack.
One by one…
all of them are defeated.
Except Sanemi.
He refuses to drop.
His breathing ragged.
His legs barely holding him up.
Kokushibo's eyes narrow.
"You still stand?"
Sanemi roars back:
"I'll stand until this castle falls apart!!"
And with a final desperate attack—
Sanemi helps land the finishing blow with the last surviving Hashira team.
Kokushibo's body fades away.
The strongest Upper Moon is gone.
---
Sans and Papyrus – Sad Reaction
Sans and Papyrus reach the battlefield moments after the fight ends.
The room is quiet.
The air is heavy.
Sanemi is kneeling alone, breathing hard, surrounded by the fallen.
Papyrus stops in place.
"H-How many… survived?"
Sans doesn't answer at first.
He takes one slow look around.
"…just sanemi."
Papyrus lowers his head.
"THESE HEROES… THEY FOUGHT SO HARD…"
Sanemi wipes his face with the back of his hand, refusing to cry.
Sans steps beside him.
"sorry we couldn't get here sooner."
Sanemi shakes his head.
"You did plenty…
Everyone did."
Papyrus places a hand on Sanemi's shoulder.
"THE GREAT PAPYRUS… IS PROUD OF YOU."
Sanemi doesn't speak—
but the smallest nod shows he heard them.
The weight of the battle hangs in the air.
And the Infinity Castle grows even darker—
because Muzan is still waiting.
Screen 8 – Scene 3: Muzan's Wrath
The Infinity Castle collapses into itself, folding like a broken mirror.
Everyone is thrown out into the night of the real world—
right in front of the remains of Ubuyashiki's mansion.
The dust clears.
And Muzan steps out.
Unscarred.
Calm.
Radiating pure hatred.
His eyes lock on the Demon Slayers with a cold smile.
"You insects… still live?"
But something is different.
Muzan touches his face.
His hand trembles.
Tamayo's drug is working.
A humanizing poison spreads through him—
slowing him, weakening him, tightening his chest.
He growls.
"That woman…"
---
The Hashira Close In
Giyu moves first, blade raised.
Sanemi follows, rage burning in his eyes.
Mitsuri and Obanai take their stances side by side.
Gyomei steps forward, presence heavy like a mountain.
Tanjiro limps in but refuses to stay back.
And right behind him—
Sans and Papyrus appear out of the drifting smoke.
Papyrus points at Muzan aggressively.
"YOU!! STOP HURTING PEOPLE!!
THE GREAT PAPYRUS DEMANDS IT!"
Sans just sighs, eye glowing faintly.
"yeah… this is the final boss for real."
Muzan stares at them all, unimpressed.
"So many of you…
yet not one can kill me."
Tanjiro grips his sword tighter.
"You're wrong.
This time… you won't escape."
---
Muzan Attacks
Black tendrils burst from Muzan's body—
fast, sharp, unstoppable.
Gyomei blocks with his flail, sparks flying.
Sanemi leaps forward, slashing away the flying strikes.
Obanai and Mitsuri dodge in perfect sync.
Giyu cuts through the tendrils with calm precision.
Tanjiro rushes in with Sun Breathing, fire roaring around him.
Sans teleports behind Muzan and fires a blaster to force distance.
Papyrus throws bone platforms to shield the injured slayers.
The entire battlefield erupts into movement.
---
The Final War Begins
Muzan lifts his arms.
"Come, then.
Prove you deserve to live."
The Hashira surround him:
Giyu
Sanemi
Obanai
Mitsuri
Gyomei
Tanjiro joins them in the center.
Sans stands behind Tanjiro with a glowing eye.
Papyrus takes a stance beside Gyomei, trembling but determined.
Tanjiro breathes deeply.
"This is it…
the final night."
Muzan smiles sharply.
"Let's end this."
The Sunrise Countdown Arc begins—
the last stand against the King of Demons.
To be continued…