No one knew how much time had passed when Chika finally opened her eyes.
Her blurred vision focused on a ceiling—familiar yet strangely distant.
For a brief moment, she almost made a quip about the "unfamiliar ceiling" trope. But really, the moment she saw it, she already knew where she was—and why she was lying in bed.
She'd tripped.
On a rock.
A tiny rock.
"…I can't believe it."
Chika sat up, burying her burning face in both hands.
She'd fought Akaza—Upper Moon Three—head-on, standing her ground blow for blow. And yet, right after that?
Defeated by a pebble. KO'd by gravity. Instantly asleep on the battlefield.
"So embarrassing…"
After a round of shame-fueled reflection, she finally calmed down.
Her mind drifted back to the fight—to the strange state her body had entered at its peak.
That power.
The speed, the regeneration, the synergy with her Crimson Blade…
In that form, she'd been far beyond her usual limits—at least one whole tier stronger.
Sure, the side effect was collapsing into a month-long coma, but still—she had to master it.
However… one small problem.
Her eyes glazed over as she muttered,
"Where do I even start? I can't exactly ask someone to beat the life out of me again. I wanna get stronger, not become a total masochist…"
The room she was in wasn't her quarters at Corps HQ.
This was one of the infirmary rooms at Shinobu Kocho's Butterfly Estate.
And unbeknownst to her, nearly an entire month had passed since she fell unconscious.
Shinobu was an expert in medicine, but Chika's body defied explanation.
Inside, every test screamed human.
But her resilience, her healing, her cell structure—belonged to something else entirely. Something… demonic.
In the end, Shinobu could only wait for Chika to wake up and explain it herself.
Incidentally, Rengoku was also recovering at the Estate. Shinobu had been genuinely surprised he'd even been walking with those kinds of injuries.
Still, his willpower was monstrous—after half a month of rest, he literally leapt out of bed, fully recovered.
For anyone else, that kind of recovery time was half a year, minimum.
During Chika's coma, Tanjiro and Nezuko had barely left her side.
For the first few days, they stayed by her bed every moment—but even they knew they couldn't keep doing that forever.
So, they turned that worry into motivation, training harder than ever, visiting her only at night.
Now it was midday.
Out in the open courtyard, Tanjiro swung his Nichirin blade again and again, performing the Hinokami Kagura.
Each slash burned through his muscles, pain searing to the bone—but he refused to stop until his arms literally gave out.
The image of his sister and Rengoku fighting Akaza burned in his mind, pushing him past exhaustion.
Not enough.
Still not enough!
Too weak!
He clenched his teeth, fiery determination in his eyes.
He needed to at least master the constant state of the Fire God Dance—to reach that next level.
Next time, he swore, he would help.
He wouldn't just stand and watch again.
As he trained, his technique visibly sharpened—his control tighter, his endurance longer.
Even Shinobu had quietly admitted his progress was frightening.
After one final strike, Tanjiro looked up at the bright noon sun and sighed. "Guess it's time for lunch…"
He turned to leave—then froze.
His nose twitched.
A scent. Familiar. Impossible.
"…This smell—" His eyes widened. "Big sister!"
In an instant, all exhaustion vanished.
His depleted body surged with new strength, and he bolted forward faster than lightning, faster than thought, faster than Bolt himself.
Out in the garden, Shinobu and Kanao were talking quietly when Tanjiro came flying past them like a hurricane.
Both women blinked in confusion.
"S-Sorry! But my sister—!"
Before he could even finish, Tanjiro had already slammed the sliding door open and dashed inside.
Shinobu and Kanao exchanged looks—then realization struck them at the same time.
"Chika… she's awake?!"
Without another word, they rushed after him.
Tanjiro reached her room first, threw open the door—
—and froze.
His pupils shrank to pinpoints.
"...S-Sis? Is that… you?"
The bed was empty.
No adult Chika in sight.
Instead, sitting at the edge of the mattress, her back turned toward him—was someone small.
At his hesitant question, the girl turned slowly, half-lidded eyes blinking lazily as she replied,
"It's me. You really don't recognize me?"
Tanjiro's jaw dropped.
It was her—no doubt about it.
But sitting there, swinging her short legs off the bed, was his eight-year-old sister.
She had literally turned into a little girl.
His mouth hung open, unable to form words.
The shock was… indescribable.
Having your sister shrink down in size like Nezuko once did?
That was a level of whiplash only the Kamado family could truly comprehend.
For Chika, it had started as a test—she'd wanted to replicate the battle-state she'd entered against Akaza.
She didn't manage that.
Instead… she'd somehow unlocked a whole new ability.
Size manipulation.
Just like Nezuko in the original story—able to shrink or grow at will.
It wasn't what she'd aimed for, but she wasn't exactly disappointed either. It was kind of… fun.
Still, being stared at so intensely by her brother made it really awkward.
A few seconds later, Shinobu and Kanao burst into the room—only to freeze in place.
Even Kanao, usually unreadable as a doll, blinked wide-eyed in visible shock.
Shinobu's mouth twitched.
She'd already struggled to understand Chika's biology before…
Now? She officially gave up.
"Y-You're… Chika, right?" Shinobu asked anyway, more out of disbelief than doubt.
"Of course I am," Chika replied flatly, dead-fish eyes half-open. "Just, uh… smaller."
Tanjiro, meanwhile, had gone silent for several seconds—until suddenly, he raised a hand.
Chika's lazy expression immediately turned serious.
"Student Kamado Tanjiro—speak."
Granted permission, Tanjiro lowered his hand and said earnestly,
"Big sis, could you stay like that for a bit? I wanna bring Nezuko to see you like this!"
The room fell silent.
Shinobu and Kanao both blinked, unable to process that reasoning.
Chika, too, looked torn between laughing and crying.
Still, she waved a hand weakly. "Approved."
"Thank you, sis!!"
And before anyone could say another word, Tanjiro spun on his heel and sprinted out of the room, a trail of dust behind him.
After all—who knew how long this "mini-Chika" form would last?
If he didn't get Nezuko here right now, he might never get another chance to see it.