The next second.
"Guaaaahhhhhh!!!"
A bloodcurdling scream, sounding unlike anything a living creature could produce, echoed throughout the Infinity Castle!
The demon's flesh and blood felt as if they had been thrown into a roaring furnace!
Its cells frantically disintegrated, then frantically reconstructed themselves!
Blue-black veins, like countless venomous snakes, writhed madly beneath its skin before bursting!
This agony far exceeded any form of torture in the world!
After a long time, the screaming finally stopped.
The demon no longer resembled a human; it lay on the ground like a puddle of mud, clinging to its last breath.
Muzan's eyes were cold. He stepped forward and directly opened the door leading to the outside world.
Blinding sunlight instantly poured in.
With a single kick, he sent the demon flying out.
"No! No!!!"
The demon erupted with an instinctive terror of the sun, desperately trying to crawl back into the shadows.
But Muzan had already shut the door, leaving it hopelessly exposed to the sunlight.
It squeezed its eyes shut in agony, waiting for its ultimate fate of turning to ash...
One second.
Two seconds.
Three seconds.
...
Nothing happened.
The expected searing pain and disintegration never came.
It opened its eyes in astonishment, raising its hands in disbelief.
Completely unharmed!
It looked up at the warm sun it had feared for centuries.
It started with a low whimper, which quickly morphed into maniacal laughter.
"Haha... Hahahaha! The sun! It's the sun!"
"I'm bathing in the sunlight! I didn't die! Hahahahahaha!"
It roared wildly under the sun, freely venting a century of fear and its current ecstasy.
However.
Right at the peak of its ecstasy.
*Squelch!*
An arm, fast as lightning and without any warning, instantly pierced through its head.
The maniacal laughter came to an abrupt halt.
The expression on the demon's face froze forever in that moment as it collapsed stiffly to the ground.
Muzan coldly retracted his arm, flicking off the blood and gore.
He did not want any potential threats around him when he consumed the Blue Spider Lily.
Not even a subordinate who normally wouldn't dare defy him.
He picked up a Blue Spider Lily, his crimson eyes burning with a greed and longing unseen in a thousand years.
The Ultimate Being, right here, right now!
He tossed the entire flower into his mouth and chewed vigorously.
The next second.
A searing pain, ten million times more violent than what that demon had just endured, explosively erupted within every cell of his body!
His body began to collapse and reconstruct!
Over ten minutes later, the extreme agony receded like the tide.
The Infinity Castle returned to a dead silence.
Kibutsuji Muzan slowly stood up. He could clearly feel that the shackles which had plagued him like a festering curse for a full millennium, the curse originating from the very depths of his bloodline, had been utterly shattered in this moment.
He looked down at his hands.
His skin was still pale, but what surged beneath it was no longer the cold, filthy blood of a demon.
Instead, it was a brand-new golden torrent, brimming with life and scorching energy.
He was, more than ever before... perfect.
"Nakime," he spoke, his voice completely devoid of emotion.
"Teleport me to the mountain peak."
*Twang!*
The biwa sounded, and space twisted.
The next instant, Muzan was standing at the summit of a mountain.
It was exactly noon.
A golden, blazing sun hung high in the sky, its radiant light tearing through the sea of clouds and spilling across the earth.
Muzan stepped out of the shadows, proactively welcoming the sun he had hated, cursed, feared, and simultaneously yearned for over a millennium.
He slowly closed his eyes.
The anticipated searing pain that would pierce his bones and burn his soul never arrived.
In its place was an indescribable warmth that seeped through his skin and into every cell of his body, making him so comfortable he almost groaned aloud.
He snapped his eyes open, staring fearlessly and directly at the blazing sun in the sky.
A scalding tear, mixed with the supreme joy of a thousand-year wish finally fulfilled, quietly slipped from the corner of his eye.
He had finally conquered the sun.
No.
It wasn't just as simple as conquering the sunlight.
He could clearly feel his power growing madly at an unfathomable speed.
Every cell in his body had transformed into a miniature solar furnace, greedily absorbing the sunlight and converting it directly into the purest, most formidable power.
He no longer needed to devour humans to sustain his life and power.
Sunlight was his greatest sustenance.
He was no longer a monarch who could only hide in the dark of night.
From this day forward, he would be the sole ruler of both day and night!
He was the Ultimate Being!
*Twang.*
As the biwa sounded once more, Muzan returned to the Infinity Castle.
He slowly walked over to the "corpse" of the puppet demon he had killed in a single strike, the corners of his mouth curling into a smile that was both cruel and somewhat divine.
He extended his index finger, forcing out a thick drop of golden blood brimming with solar energy from his fingertip.
The blood dripped down, merging into the demon's pierced skull.
Visibly, the horrific wound healed madly at a speed defying all logic, flesh and blood regenerating.
The next second.
The demon abruptly opened its eyes.
However, those eyes no longer held any light of their own; all that remained was absolute emptiness and the most primal loyalty to the god standing before it.
"You have no name, no past. You are merely an extension of my will."
Muzan declared, looking down at it from above, "I grant you the right to walk beneath the sun."
"Now, go to the human capital. Use your abilities to control the Daimyo of this country."
...
Meanwhile, the Demon Slayer Corps' special training had reached a fever pitch.
Within an endless hellscape of fire.
"Flame Breathing, Ninth Form: Rengoku!"
Kyojuro Rengoku let out an earth-shattering roar. His entire body burned with materialized flames as he launched a desperate, death-defying charge at the towering, immovable figure ahead!
However, Yamamoto Genryusai Shigekuni merely lifted his eyelids slowly and swung his sword casually.
*Boom!*
The moment Kyojuro's body and flames touched the blade, they were completely incinerated, turning into nothingness.
A few breaths later, his form condensed once again within the sea of fire.
His eyes, far from showing any discouragement, burned with an even more scorching fighting spirit!
"Again!"
...
In another courtyard.
It was noon, and the scorching sun hung high in the sky.
"Sun Breathing: Dance!"
Tanjiro Kamado gave it his all, the Nichirin Sword in his hands drawing a perfect arc of fire as he slashed at the man who was as burly as a mountain.
However, Escanor could not even be bothered to look at him.
He simply stood there arrogantly, allowing the fiery slash to land on his body.
*Clang!*
With a crisp sound, Tanjiro's sword bounced off Escanor's muscles. He was sent flying backward, crashing miserably to the ground.
Not a single scratch was left on Escanor's body.
"Too weak, brat."
Escanor glanced at him with a disdainful look.
"This so-called 'sun' of yours doesn't even qualify to tickle me."
Tanjiro coughed up a mouthful of blood, yet he stubbornly stood back up.
He could feel that every time he was repelled by Escanor's overwhelmingly domineering aura, the 'sun' aura within his own body became a fraction more condensed.
...
"Beast Breathing, Ninth Form: Thunder Bagua!"
Inosuke Hashibira kept his eyes closed, sensing everything around him.
Suddenly, he snapped his eyes open and crossed his dual swords in front of him to block! A pitch-black power traveled up his arms and onto the blades.
*Clang!*
A massive spiked club, carrying the momentum to destroy everything, smashed ruthlessly against his swords!
The terrifying force sent him flying like a cannonball, smashing through over a dozen large trees before finally coming to a stop.
"Hmph, brat, that's not how you use Haki!"
A voice like roaring thunder echoed from the dust.
"Get back on your feet!"
...
On the other side.
Zenitsu Agatsuma was frantically weaving through a training ground littered with kunai at a speed surpassing his limits, dodging attacks fired from all directions.
His movement speed was more than several times faster than before!
"Very good, Zenitsu."
Minato Namikaze's gentle voice rang in his ears.
"But having speed and reaction time alone isn't enough. Next, we'll begin practicing taijutsu and strike resistance."
"Gyaaaahhh! Spare me! Minato-sensei!"
Zenitsu's miserable screams echoed into the clouds.