The next day, Nezuko awoke from her deep slumber.
Inside the Butterfly Mansion's courtyard, nearly everyone had gathered.
Even Giyu Tomioka, upon hearing the news, had hurried over to witness the miracle once again.
Hand in hand, Tanjiro slowly led Nezuko toward the sunlight.
And when Nezuko stepped fully into the sun without suffering any harm, everyone erupted in joyous cheers—while Tanjiro was already weeping tears of overwhelming relief.
Falling to his knees, Tanjiro pressed his forehead to the ground and said sincerely,
"Truly… thank you, everyone. Without all of your help, Nezuko and I might never have seen this day."
Yōsuke stepped forward to lift Tanjiro up.
"This is the result of your own efforts. If you hadn't refused to give up on Nezuko and kept fighting all this time, even with our help, none of this would have been possible."
Tanjiro looked at Yōsuke—his mentor and father figure—with heartfelt emotion.
To Tanjiro, the two people he respected most were his master, Sakonji Urokodaki, and the man who had helped him countless times, Yōsuke.
Zenitsu, staring blankly at the still-dazed Nezuko, asked curiously,
"Why hasn't Nezuko regained her consciousness yet?"
Shinobu Kochō explained,
"The medicine's effect only allows her to withstand sunlight. It doesn't restore her consciousness."
Tanjiro gently stroked Nezuko's hair.
"That's enough. Maybe it's better if she forgets all those painful memories."
With Nezuko's success as proof of concept, the Kochō sisters and Tamayo's confidence soared.
New ideas for the human transformation medicine flooded their minds, and they eagerly returned to their research.
While the Butterfly Mansion brimmed with laughter and warmth—the Infinite Castle was shrouded in oppressive gloom.
There were countless chambers within the Infinite Castle, and Kibutsuji Muzan sat alone in the main hall, drowning in self-doubt.
His forces had dwindled to a mere shadow of their former might.
Of the Twelve Kizuki, only Doma, Hantengu, Nakime, and Kaigaku remained.
Muzan had once pinned his hopes on the Divine Priest Clan to help him conquer the sun—but that dream, too, had crumbled to dust.
For the first time in a thousand years, Kibutsuji Muzan felt lost.
He had created countless demons, yet still found no trace of the Blue Spider Lily.
He had believed the Divine Priest Clan could help him overcome the sun, but even after finding them, their bloodline proved useless.
Despite being an existence nearly perfect—a being of eternal life—that single weakness, his fear of sunlight, lodged in his heart like a fishbone caught in his throat.
Now the Demon Slayer Corps had reached its strongest point in history, exterminating demons across the land.
And as furious as Muzan was, he could do nothing against them—because an even greater threat stood in his way: Yōsuke Ubuyashiki.
Since becoming a demon himself, Yōsuke had pursued Muzan like a rabid dog, never letting him rest.
Once Yōsuke found an opening, he would fight without fear of death—
even dragging Muzan down to hell if that was what it took.
Muzan could not comprehend Yōsuke's mindset.
To him, humans should be nothing more than insects, easily crushed beneath his heel.
Yet this one refused to yield.
Of the Twelve Kizuki, only four remained.
Even with their combined might, holding back the Demon Slayer Corps was a struggle—
let alone dealing with the demons Yōsuke himself had created, each one possessing power on par with the Upper Moons.
If Muzan chose to gamble everything now and launch an all-out war against the Demon Slayer Corps and Yōsuke,
the outcome was clear: the four remaining Upper Moons would barely buy him time,
and Muzan himself would have to face Yōsuke directly—a battle that might once again drive him to the brink of annihilation.
It was a deadlock.
To overcome sunlight, he still needed the Blue Spider Lily.
But after a thousand years, he hadn't even found a single leaf.
Meanwhile, the Demon Slayer Corps and Yōsuke kept tightening the noose around him.
The dream of becoming the ultimate lifeform—free from the sun—was slipping further and further away.
As Muzan brooded, a sudden, bone-deep chill ran through him.
Every hair on his body stood on end.
He sensed an aura behind him so terrifying it made his soul tremble.
Whipping around, Muzan saw nothing—
and the presence vanished as suddenly as it had appeared, as if it had never existed.
But when he turned back, a man was now sitting cross-legged before him.
Instinctively, Muzan lashed out with his blood whips.
"Word Spirit: Reject."
The man's voice was clear and ethereal.
An invisible force shattered Muzan's attack and sent the tendrils flying.
Muzan's expression grew grim.
Whether it was a Demon Slayer's Breathing Technique or a demon's Blood Demon Art, both released distinctive energy signatures when used.
Yet the man before him emitted none whatsoever.
Moreover, the Infinite Castle could not be entered without Muzan's or Nakime's permission.
Muzan narrowed his eyes and demanded,
"Who are you?"
The man's expression was utterly calm, devoid of joy or sorrow.
"Aren't you the one who's been looking for me, Kibutsuji Muzan?"
"The Divine Master?!"
Muzan froze for a moment—then his face twisted into wild delight.
He hadn't expected the Divine Master to appear before him of his own accord.
Immediately, Muzan lashed out again with his whips, trying to bind the man.
But—
"Word Spirit: Force."
The Divine Master's quiet command unleashed an overwhelming gravity that slammed Muzan to the ground, immobilizing him completely.
Muzan's eyes widened in disbelief.
For a thousand years, only one man—Yoriichi Tsugikuni—had ever been able to suppress him like this.
Not even Yōsuke Ubuyashiki had such power.
The Divine Master looked down at the pinned Muzan with indifference.
"I've come this time to propose a collaboration."
At that, Muzan suddenly recalled what the suicidal priest of the Divine Clan had said:
When the line between humans and demons blurs, the Divine Master himself will appear.
His eyes widened in shock.
"Could it be… someone has already overcome the sun?! Who is it? Yōsuke Ubuyashiki?!"
The Divine Master's tone remained cold.
"It is not Yōsuke Ubuyashiki. The ones who have conquered the sun are Kokushibo and Nezuko Kamado."
Muzan's hands clenched so tightly his claws pierced his palms, blood dripping to the floor.
He seethed with fury.
"What I have sought for a thousand years—something I could never attain—they've achieved it?! I will devour them! The only one worthy of conquering the sun is me! Only I!"
The Divine Master's voice carried a faint trace of mockery.
"Do you truly think you can manage that now?
Kokushibo's survival in sunlight means he's regained the right to wield the Sun Breathing technique.
And there's also the child of destiny—Tanjiro Kamado—who has already mastered it.
Meanwhile, you… can do nothing but cower in the shadows of the Infinite Castle like a beaten dog."