The tranquility of the Ubuyashiki Estate and the Butterfly Mansion was shattered in an instant by a sudden sound.
TING!
A single note from a biwa rang out, carrying overwhelming penetrating force.
Rin, standing in the corridor of the Butterfly Mansion, narrowed his eyes slightly.
"It's here."
The moment his words fell, the ground beneath their feet vanished without warning.
Japanese sliding doors painted with ukiyo-e patterns appeared out of thin air, opening one after another beneath their feet, above their heads, and throughout the surrounding space.
In that instant, the very concept of space was overturned, and gravity lost all meaning.
"Ah!"
Shinobu Kocho, who had been carrying medicine, felt the floor disappear beneath her. A powerful sense of weightlessness struck her, and she fell uncontrollably toward the endless wooden abyss below.
Before she could even draw the short blade at her waist, a strong arm wrapped around her slender waist, pulling her firmly against a broad chest.
"Don't panic. Hold on to me," Rin's deep, steady voice sounded beside her ear.
In the next moment, a surge of deep purple-red chakra burst from Rin's body.
The immense energy rapidly took shape in midair, forming a half-body Susanoo composed of skeletal ribs and arms, shielding Rin and Shinobu within its core.
"Waaaaah! Help! I'm falling into hell!"
Not far away, Zenitsu Agatsuma flailed wildly in midair, his cries echoing miserably as he tumbled.
Tanjiro Kamado tried to steady himself, adjusting his posture mid-fall, while Inosuke Hashibira excitedly swung his dual blades, shouting about slicing all the flying wood to pieces.
The giant skeletal hand of the Susanoo shot out, grabbing the three noisy troublemakers like chicks and pulling them into its palm.
"Quiet down, or I'll drop you," Rin said coldly.
Zenitsu immediately clamped his mouth shut, nodding frantically through tears.
At the same time, the Hashira at the Ubuyashiki Estate were experiencing the same upheaval.
Yet thanks to the hellish training of the past month, each of them displayed astonishing reflexes in the face of this sudden crisis.
"Wind Breathing, Fourth Form: Rising Dust Storm!"
Sanemi Shinazugawa swung his blade upward midair, the force of the wind slash propelling him onto a floating wooden staircase.
Gyomei Himejima hurled his spiked flail, the chain wrapping tightly around a thick beam, allowing him to swing down and land steadily.
Kyojuro Rengoku, Giyu Tomioka, and the others each used their own movement techniques, finding footing within this twisted, inverted, and chaotic space.
Everyone looked around, shock filling their eyes.
This was an endless underground city. Countless pavilions, corridors, and stairways overlapped in ways that defied all physical laws—bottomless and impossible to reach the end.
The Infinity Castle.
Kibutsuji Muzan's absolute domain.
"Welcome to my castle, you foolish Demon Slayers."
A cold, arrogant voice echoed through every corner of the Infinity Castle, carried by Nakime's Blood Demon Art.
"Ubuyashiki Kagaya, did you really think gathering all your forces would allow you to contend with me? How naive. Tonight, this place will become the graveyard of the entire Demon Slayer Corps. I will devour you all, along with that demon named Nezuko!"
As Kibutsuji Muzan's declaration fell, countless sliding doors throughout the Infinity Castle burst open at once.
From every direction, thousands of grotesque, foul-smelling lower-ranking demons poured out like a tide, crawling along wooden walls and stairways as they rushed madly toward their prey.
"A graveyard? You're certainly confident in your shell."
Standing atop the Susanoo's palm, Rin's pitch-black pupils transformed into the scarlet Eternal Mangekyō Sharingan.
His voice, infused with immense chakra, directly overwhelmed Muzan's broadcast, causing the entire Infinity Castle to tremble.
"You vermin who've been hiding in the dark for a thousand years are only capable of tricks like trapping others in a cage."
Rin raised his right hand. Azure lightning gathered wildly in his palm, releasing the piercing cry of a thousand birds.
"But you've made one mistake. You didn't trap us in here—you trapped yourself in here with monsters."
"Lightning Release: Chidori.. Great Splitting Flash!"
Boom—!!!
From Rin as the center, hundreds of high-pressure lightning bolts as thick as barrels exploded outward, sweeping across the intricate wooden corridors and stairways!
The front ranks of demons didn't even have time to scream before they were reduced to charred ash, obliterated by the violent surge of lightning.
Blinding arcs of electricity illuminated every dark corner of the Infinity Castle like daylight.
At the sight of this, the tension in the Hashira instantly turned into surging battle intent.
"Hmph! Lord Rin is right! This is not our graveyard, but the final hunting ground to slay Kibutsuji Muzan!"
Flame Hashira Kyojuro Rengoku roared, the flame-shaped Demon Slayer Mark on his forehead igniting at once.
"Everyone! Slay every demon! Do not let Lord Rin fight alone!"
"Just what I wanted! I'll tear this broken castle apart!"
Wind Hashira Sanemi Shinazugawa laughed wildly as he charged into the swarm, his wind blades shredding through demons like a storm of blades.
Clang—!
Just as the slaughter was about to begin, the sharp sound of the biwa rang out once more.
Nakime plucked the strings of her biwa.
She had received a direct order from Master Muzan: separate these troublesome Hashira, then use the terrain and the Upper Ranks to eliminate them one by one.
Rumble~~!
The space of the Infinity Castle twisted and folded violently.
Connected stairways snapped apart, and wooden walls flipped in every direction.
Flame Hashira Kyojuro Rengoku, Wind Hashira Sanemi Shinazugawa, Water Hashira Giyu Tomioka, and the others all lost their footing as the ground beneath them vanished, forcibly transported to unknown areas within the castle.
"Spatial Blood Demon Art, huh."
Rin looked at the warped surroundings and let out a cold snort.
He could feel a powerful spatial force trying to tear him away from Shinobu, Tanjiro, and the others beside him.
If it were his former Mangekyō Sharingan, dealing with this large-scale spatial displacement might have been troublesome.
But now, with the Eternal Mangekyō Sharingan and the foundation of Yin Release and Yang Release, as long as he resisted, this level of spatial manipulation couldn't move him at all.
"Tanjiro, take the two of them and follow the scent to regroup with the Hashira."
Rin kicked the three of them toward a sliding door that was about to close, while his left hand tightly gripped Shinobu's wrist.
"As for you, don't even think about taking anyone from me."
The pattern in the depths of Rin's eyes spun rapidly as vast chakra surged out, forcibly anchoring a coordinate within the distorted space.
A wave of dizziness followed as the surrounding space sealed shut.
When his vision cleared again, Rin and Shinobu had landed in a spacious chamber.
The temperature here was extremely low, and tiny ice crystals floated through the air.
At the center of the room lay a large indoor lotus pond.
"Ara, Nakime is quite thoughtful, sending me such lovely guests."
A smooth, honeyed voice drifted out from the center of the lotus pond.
The moment Shinobu Kocho heard it, her pupils shrank sharply.
Her blood seemed to run cold, and the hatred buried deep in her bones made her grip on the sword hilt tremble uncontrollably.
Seated upon an ice throne in the lotus pond was a young man with long, pale white hair, his head stained as though splashed with fresh blood. He lazily waved a golden iron fan, his rainbow-colored eyes fixed on them with a smile.
Upper Rank Two, Doma.
"I recognize that haori. There was a female swordsman who used Flower Breathing who wore it before. Her scent… truly nostalgic." Doma tapped his chin lightly with his fan, letting out a theatrical sigh. "It's a pity it was already dawn back then. I couldn't eat her. Such a shame."
"You… you monster!!!"
The moment Shinobu Kocho heard those words, something inside her snapped. The butterfly-shaped Demon Slayer Mark at her neck ignited instantly as she drew her short blade, ready to charge forward without hesitation.
A warm, powerful hand pressed firmly onto her shoulder, stopping her in place.
"Calm down."
Rin pulled her behind him, his voice steady, yet carrying an authority that could not be resisted.
He lifted his gaze, his dark eyes locking coldly onto Doma seated upon the ice throne.
"I already said it before. The death of this fan-waving freak will be a gift from me to you."
Rin flicked his Kusanagi sword into a reverse grip, purple-black lightning crackling along its blade as the tip angled toward the ground.
"Didn't you just say it was a pity you couldn't eat your fill?"
A cold, cruel smile formed at the corner of Rin's lips.
"Today, I'll treat you to a feast hot enough to burn even your soul."
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