Inside a small cabin at the mountain's base, Nezuko was fast asleep, her soft breathing the only sound in the room.Across from her, Chika Kamado sat face-to-face with Sakonji Urokodaki.The air between them was tense, heavy with unspoken questions.
"Girl," Urokodaki began, his voice deep behind the tengu mask, "can you remove your clothes?"
"…Huh?"
Even though Chika had mentally prepared for something like this, the words still hit her like a hammer. Her expression twitched uncontrollably.
Old man Urokodaki… I know you're not that kind of person, but still—can you not say it like that?!
"You mean… you want to check my wounds, right? This much should be enough."She calmly tugged at her clothing, exposing one shoulder. A deep scar stretched downward, vanishing beneath the fabric.
Behind the mask, Urokodaki's eyes narrowed slightly. He'd expected injuries—but this was worse than imagined.
A normal person shouldn't even be standing after sustaining something like that. Her breathing should be faint, her body frail. Yet…
He leaned closer. The wound was faintly pulsing—healing itself.
"Incredible…" he murmured. "It's already regenerating. At this rate, it might heal completely—without even a scar. That level of recovery is far beyond any human capability."
"So," Chika asked quietly, "what are you saying?"
"I suspect your body has undergone a change," Urokodaki said. "Perhaps similar to your sister Nezuko's—but different. You're not harmed by sunlight, and if you feel no bloodlust or hunger for humans, then this transformation is…"
He trailed off, realizing his excitement was showing.
And who could blame him? Such a phenomenon defied everything the Corps knew.Demons gained their power at the cost of sunlight and sanity—yet this girl seemed to have evolved, not devolved.
If it was truly evolution—a being stronger than a human, yet free from demonic weakness—then the balance of a thousand years of struggle could change forever.
If this power could be replicated, Urokodaki thought, the Demon Slayer Corps might finally turn the tide.
But if this evolution came from demon blood, it would cause division among the ranks. That, too, had to be considered carefully.
Chika, watching his silent calculation, could guess what expression he wore beneath the mask.
Her body was undeniably strange.Her wounds were closing, the pain fading.She felt no hunger for flesh or blood.The sunlight didn't burn her.Yet within this fragile frame, she could sense something else—a quiet, sleeping strength that felt limitless.
Hours passed.
Outside, footsteps approached the door—thump, thump, thump.The door slid open, and Tanjiro stumbled in, gasping for breath, blood trickling down his forehead.
"I… I'm back…"
He collapsed onto the floor the next second.
Urokodaki turned his gaze toward him, then glanced at the window—judging the time by the light.
That fast?
The boy had already cleared the test. His endurance and resolve exceeded expectations.
A boy with unshakable faith,a demon girl who defied her hunger,and now, a young woman who embodied evolution itself.
Urokodaki let out a low hum behind his mask.
"…Interesting."
Then he spoke aloud: "Training begins tomorrow."
The Next Morning
Tanjiro was up before sunrise. Urokodaki began by teaching him about demons—their anatomy, their weaknesses, their regenerative properties.
Tanjiro listened intently, eyes wide in awe, occasionally jotting down notes.
Chika sat nearby, listening as well. She already knew most of it—but pretending to be attentive was polite.
When the lessons ended, Urokodaki began the physical training.He set traps across the mountains and ordered Tanjiro to run, dodge, and climb until he could cross them all without being caught.
Then came sword drills—Urokodaki handed him a practice blade to simulate real combat.
Chika, still recovering, could only watch from the side.But every day, she felt the difference.Her healing wasn't just fast—it was accelerating.
Within a single week, every wound had vanished—no scars, no pain.And for the first time since that night, she felt whole.
When Tanjiro completed the mountain trap course, it was time to begin swordsmanship training.
That day, as Urokodaki spoke to Tanjiro, Chika stood up from her wheelchair. Slowly, deliberately—one step, then another—she walked toward them.
"Mind if I join you?" she asked.
Tanjiro spun around in shock, nearly dropping his sword."S-Sister?! You're standing?! The wheelchair—"
Thud!
Before he could finish, a fist dropped onto his iron-hard forehead with a loud crack.
"Ow—!"
"Can we not mention the wheelchair every five minutes?" Chika said flatly. "It's been a week. I'm not staying in that thing forever."
Tanjiro blinked, utterly lost.Is it really normal to recover from wounds like that in a week?
Urokodaki watched silently.Even behind the mask, his eyes gleamed.
This was no frail girl anymore. Her skin glowed with health, her reddish hair gleamed under the light, and though she shared the Kamado warmth, she carried herself differently from Nezuko—a serene beauty with quiet resolve.
"Very well," Urokodaki said at last. "You can train with Tanjiro."
He handed Tanjiro one of his wooden swords, then offered another to Chika.
There was no more hesitation.As the two siblings took their stances, Urokodaki straightened his posture.
Before teaching them the Breath of Water, they first needed to learn the basics—the flow of the sword, the rhythm of the body, the unity of breath and strike.
He'd expected this to take two years.But as the days went on, he would realize… his expectations were far too low.