"This is the last time, Nezuko. There won't be a next one!"
Chika sighed helplessly.
Her words were forgiving, but her hands certainly weren't.
Bonk!Bonk!Bonk!
Her hand-chops rained down on Nezuko's forehead like a temple monk striking a wooden fish. Nezuko swayed in place, eyes dazed from the rhythmic punishment.
Of course, Tanjiro didn't escape her wrath either.
Yes, he had run off purely out of worry—but that was no excuse.
Chika turned toward Tanjiro, then glanced past him at Zenitsu and Inosuke. "You all look like you've been progressing well with Constant Total Concentration," she said lightly. "That means your current schedule is getting a little too easy. How about I add a few more lessons?"
Zenitsu stiffened instantly. A sense of doom flooded through him.
"W–wait, not—!"
Before he could finish, Tanjiro clamped a hand over his mouth, and Inosuke promptly locked him in a chokehold.
"Hahaha! No problem at all!" Tanjiro said cheerfully, muffled yelps escaping from under his palm. "Zenitsu and Inosuke are almost done with their current training anyway. We'd love to do more!"
"Exactly!" Inosuke said, flexing an arm around Zenitsu's neck. "Whatever the boss says—we'll do it! I'll do anything to get stronger!"
"Excellent! I like that enthusiasm!"
Chika smiled with approval, while Zenitsu made strangled noises of despair.
Zenitsu (internally): 'I'll try harder, I'll train, I'll… I'll outwork you all, I swear!!!'
The next few days could only be described as brutal beyond reason.
Especially for Zenitsu and Inosuke, whose mastery of Constant Total Concentration wasn't complete. On top of maintaining their breathing around the clock, Chika had saddled them with new training modules that left even Inosuke questioning his life choices.
The additions were simple but merciless: grip-strength conditioning and mock combat drills.
For the Hashira, manual ignition of the Red Blade was possible through sheer willpower. But for these three rookies? Not a chance.
Chika knew that. So instead of expecting miracles, she focused their lessons on cooperative resonance—the technique of heating Nichirin Blades through friction and synchronized strikes.
While the boys groaned and sweated through their impossible regimen, Chika and Nezuko trained side by side in the sunlight.
"The Water Breathing forms are the most fluid of all," Chika explained, holding her blade lightly. "Don't force it. Water adapts—it doesn't fight. Feel it flow."
"Yes, Big Sister!" Nezuko responded brightly.
Chika wasn't the best teacher, but she was far from unqualified.
If Water Breathing were graded on a ten-point scale—
Then Giyu Tomioka, the current Water Hashira, would be a perfect 10.
Former Hashira Sakonji Urokodaki, in his prime, would have been a solid 9.
As for Chika and Tanjiro—both stood at around 8, making them more than capable of guiding Nezuko, who was still a complete beginner.
Nezuko trained eagerly, the sunlight warming her skin as she moved. For the first time, she could practice outdoors, basking under the sky. Her spirit soared with every swing.
If a demon no longer hungers for humans—and no longer fears the sun—then what truly separates a demon from a human anymore?
The air around them was serene, almost peaceful.
But just a short distance away—chaos reigned.
"I… I can't anymore… I need… a break…" Zenitsu gasped, staggering toward the house.
He didn't make it far. A pebble caught his foot—
Thud!
He collapsed face-first into the dirt, unconscious.
"Zenitsu!" Tanjiro and Inosuke dropped their swords and rushed over.
"Zenitsu! Are you—"
Before they could finish, Zenitsu's body twitched. Then, eerily calm, he stood up.
Eyes closed. Breathing steady.
The air around him changed. His aura deepened, filled with pressure. His previously shaky Total Concentration became fluid, natural—perfect.
"Z–Zenitsu?" Tanjiro stammered, swallowing hard.
The next instant—Zenitsu vanished.
A streak of lightning shot across the courtyard as he resumed his training routine at impossible speed.
"I'll outwork you… I'll outwork you… I'll outwork you all!!!" he muttered, voice half-asleep, half-demonic.
Tanjiro and Inosuke blinked, dumbfounded, then exchanged uncertain looks.
"…He's fine, right?"
"Probably?"
They both exhaled in relief, then laughed awkwardly and returned to their drills.
No matter how exhausting, the sense of growth—the thrill of becoming stronger—made every drop of sweat worth it.
Chika, watching from the side, couldn't help smiling.
There was something beautiful about it: not sudden leaps in strength, but steady, relentless progress. Building a tower of effort, one stone of determination at a time.
While guiding Nezuko's breathing, Chika continued her own discipline—feeding her will and heat into her Nichirin Blade, tempering her control over the Red Blade ignition.
Practice upon practice, repetition upon repetition.
Now, she could heat the blade within five seconds through pure focus—a remarkable feat. Yet she knew it still wasn't enough.
Not yet.
The entire compound buzzed with effort. Training cries, sword clashes, and deep, rhythmic breathing filled the air.
Then a warm, familiar voice broke through the noise.
"Ahahaha! I knew it—I could sense the fiery spirit from here!"
Chika turned.
At the gate stood Kyojuro Rengoku, the Flame Hashira himself.
He raised an arm to wave—then froze mid-motion.
Because right beside Chika… stood Nezuko.
Under the blazing sun.
Sword in hand.
Practicing Water Breathing.
Rengoku's eyes widened, his jaw hanging open.
A demon… standing in sunlight? Training with a sword?
After a long pause, he threw back his head and laughed—a booming, joyful sound.
"Chika! You truly are… extraordinary!"
He grinned from ear to ear, fire dancing in his eyes.
"You've created another miracle!"