The Hashira training in the deep mountain valley had continued for a full month.
With the support of Yang Release chakra—an almost unreasonable "medical cheat"—the Hashira of the Demon Slayer Corps had endured hundreds of near-death experiences.
Now, each of them had mastered the method of activating the Demon Slayer Mark, and their overall combat strength had surged to an unprecedented level.
These swordsmen, long suppressed, were eager for battle, wishing they could charge straight into the demons' stronghold and wipe out the Twelve Kizuki in one sweep.
But Rin knew very well that searching for Kibutsuji Muzan across vast mountains and forests would be far too inefficient.
That ancient monster, who had lived for a thousand years, possessed exceptional methods of concealment and escape.
As long as he retreated into the separate dimension of the Infinity Castle, no one could even touch a strand of his hair.
To make him willingly crawl out of that safe shell, one needed to cast bait.
Something so irresistible that he would bite even at the risk of being hooked through the throat.
Rin's gaze shifted to Kamado Tanjiro, who was practicing sword swings beneath the waterfall, cutting against the current.
At noon, the sun blazed overhead.
Rin brought Tanjiro—still carrying the wooden box on his back—away from the training ground to a wide, open meadow.
"Rin-san, what are we doing here? I still have three thousand swings left for today," Tanjiro asked, wiping the sweat from his forehead, confusion clear in his voice.
"Put the box down and open it."
Rin went straight to the point.
Tanjiro froze. He glanced at the scorching sun overhead and hurriedly waved his hands.
"No! It's midday, and there isn't any shade here. If Nezuko comes out, she'll be burned by the sunlight!"
"She won't."
Rin crossed his arms, his tone firm.
"The Kamado family's bloodline is special. The flaw in Nezuko's body—the part that feared sunlight as a demon—has already been assimilated and repaired. She can now walk under the sun. If something bad starts to happen, I'll put her inside the box under one-tenth of a second."
Tanjiro froze, his mouth slightly open.
But out of complete trust in Rin, he still stepped forward and unlatched the wooden box.
Creak.
The lid slowly opened.
Nezuko, curled up inside, cautiously poked her head out. Faced with the blinding sunlight, she instinctively shrank back, trying to retreat into the shadows.
But when she hesitantly extended her fingertips and touched the golden light, the searing pain she expected never came.
Instead, what wrapped around her fingers was a gentle warmth that belonged to the human world.
Nezuko stared blankly at her palm, then slowly climbed out of the box.
Her feet touched the soft grass as she stood fully beneath the blazing sun.
A breeze passed, lifting her long black hair.
She raised a hand and removed the bamboo muzzle from her mouth. From her dry throat came unfamiliar, halting words.
"Good… morning… Brother."
Tanjiro's eyes instantly reddened, tears streaming down his face.
He rushed forward, pulling his sister—returned to her human form—into a tight embrace, sobbing uncontrollably.
This was a scene he had dreamed of countless times.
Rin stood to the side, not disturbing their reunion.
His gaze casually swept toward a patch of bushes at the edge of the meadow.
Deep within the layered shadows of the leaves, an eyeball veined with blood, the character "Four" etched into its pupil, stared intently at Nezuko standing under the sunlight.
It was one of the surveillance eyes spread by the new Upper Rank Four, Nakime.
After losing two Upper Rank demons at the Swordsmith Village, Kibutsuji Muzan had refrained from deploying his main forces. Instead, these silent eyes had spread across much of Japan like a web.
Rin had already noticed this one tracking them days ago.
He had deliberately brought Nezuko to this open, unobstructed meadow to put on a show for the watcher lurking in the shadows.
Judging by the timing, Kibutsuji Muzan should have already received a clear enough image.
Rin slowly turned his head, his gaze cutting across the meadow to meet the eyeball hidden within the bushes.
"Did you see it clearly? The thing you've spent a thousand years searching for is right here."
He raised his right hand, a faint trace of blue lightning dancing at his fingertips.
"If you have the courage, come and take it yourself."
Pop.
A streak of lightning flashed past, striking the hidden eyeball with perfect precision, reducing it to a wisp of smoke that carried a scorched stench.
...
At the same moment...
Deep within the Infinity Castle,
Kibutsuji Muzan sat among scattered experimental equipment, flipping through an ancient text with a dark expression.
Suddenly, Nakime's shared vision forcefully flooded into his mind.
The instant he saw the girl with the bamboo muzzle standing unharmed beneath the blazing sun, his thoughts went blank.
Then, in the very next moment, an overwhelming ecstasy drowned out all reason.
"The sun… she has conquered the sun!"
Kibutsuji Muzan shot to his feet, the ancient book slipping from his hand and falling to the floor.
His extreme agitation caused his body to distort involuntarily. Large patches of dark red keratin surfaced across his pale skin, and his arms showed faint signs of transforming into sharp, whip-like bone structures.
"A thousand years!"
For a thousand years, he had hidden like a creature that could not face the light, searching endlessly for the elusive Blue Spider Lily.
And now, the key to perfection—the vessel that could elevate him into a true ultimate being—had appeared alive before his eyes.
As long as he devoured that special existence, he could complete the final flaw in his genes.
"No need to search for the flower anymore! As long as I devour that demon, Nezuko, I can conquer the sun! I will become the perfect, ultimate lifeform!"
Kibutsuji Muzan's eyes turned bloodshot, a suppressed, beast-like growl rumbling from his throat.
"Nakime. Halt all meaningless peripheral surveillance. Gather all the eyes and focus entirely on locating the exact position of the Ubuyashiki Estate."
"Once I lock onto its coordinates, I will drag those irritating swordsmen—and that demon Nezuko—into the Infinity Castle!"
Within the Infinity Castle, the shifting and inversion of space were entirely under his control.
He could easily separate the Demon Slayers and exhaust them with an endless tide of demons.
"On my ground, even that monster will be forced to await death."
____
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