Crossover: The Problematic Deity of Arcadia

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Demon Slayer World – Butterfly Mansion 

In a quiet room filled with the scent of herbs and polished wood, Kanae Kocho sat at her desk, twirling a pen between her fingers and staring at her open notebook.

"Hm… I've sent so many messages, but there's still no reply. That's weird. You'd think a demon wouldn't pass up the chance to talk to a human, right? Normally, they'd be thrilled if their food came knocking on their door…"

She paused, tapping the pen against her chin thoughtfully.

"Don't tell me… could it be that he's scared of me because I'm a Hashira? Is that it? He's too afraid to even respond?"

Kanae let out a soft sigh, disappointed at the silence from her mysterious 'demon friend.'

From the adjacent room, a familiar, exasperated voice rang out:

"Kanao, brush your teeth! And don't swallow the foam."

"…Mm."

"Kanao, wash your face. And remember to put the basin back properly."

"Mm."

"Kanao, once you're done, don't just stand there—come eat. When you finish, put your dishes in the kitchen. I'll wash them later."

"…Mm."

"Kanao…"

Call after call echoed through the halls until, finally, there was a loud thud as the sliding door slammed open.

"Big sis! You have to do something about this kid!"

The voice belonged to Shinobu Kocho, and while it started out irritated, it quickly dipped into utter despair.

"She won't do anything unless I give her direct instructions! I mean, seriously—every single step has to come from me! She has zero initiative!"

Kanae turned toward her sister with a calm smile.

Shinobu had raven-black hair that faded into a dark purple hue at the ends, styled in soft waves. Her large eyes lacked visible pupils, instead shimmering with a gradient of purple. Her hair was always neatly tied, her appearance consistently tidy and composed.

But right now? She looked like she was one sleepless night away from a breakdown.

"When is this ever going to end?" Shinobu groaned.

It wasn't that she disliked Kanao Tsuyuri. Far from it. But between her own packed schedule—breathing technique practice, sword training, pharmacology, treating patients at the Butterfly Mansion, and carrying out demon-hunting missions—Shinobu barely had time to breathe.

And now? Now she had to babysit a girl who couldn't even decide when to sit down unless told.

It was exhausting.

Since Kanao demanded her attention all day, Shinobu was forced to cram all her other duties into the night. She hadn't gotten more than three hours of sleep a night for nearly two weeks now.

Something had to give.

Seeing her sister so stressed, Kanae offered gently, "Then how about I take care of Kanao for a while?"

"No way!"

Shinobu shot that idea down before Kanae even finished her sentence.

"You're a Hashira. You've already got a million things to deal with. If you overextend yourself and burn out, fighting demons will become way too dangerous."

She paused, then added with a serious look:

"Besides, you spoil her too much. You're going to turn her into a complete freeloader!"

Kanae blinked, a little flustered. "That's only because she's just too cute~"

"Exactly why I can't let you raise her!"

Shinobu huffed, then sighed heavily.

"…Alright. I'll just ask the Corps for some time off."

Kanae opened her mouth to object but thought better of it. Truth be told, if Shinobu took a break from demon-hunting, she'd be much safer. So she held her tongue.

Shinobu, meanwhile, was still grumbling to herself. "Seriously. I just hope she grows up a little, and soon."

Just then, Kanae caught sight of Kanao and immediately broke into a doting smile.

"Kanao~ Did you eat enough breakfast?"

"Mm." Kanao nodded blankly, her gaze fixed on Kanae.

Kanae's smile grew even warmer.

"That's good. If you're still hungry, I'll whip up something extra just for you."

"…Mm." Another nod.

And that was it. No reaction, no change in expression.

Watching this, Shinobu groaned and held her forehead.

"Big sis! She's a girl, y'know! If you keep feeding her like that, she's going to get chubby!"

Kanae looked genuinely puzzled.

"Eh? But aren't kids supposed to eat a lot to grow strong and healthy?"

"…"

Shinobu didn't even bother replying this time. She'd already made up her mind—Kanae was absolutely not allowed to be in charge of Kanao's upbringing.

Too much love ruins a child.

Suddenly, Kanae glanced back at her notebook, then stood up and approached Kanao with a gentle expression. She reached into the pouch tied to her waist and pulled out a coin.

It was a copper coin, marked with "Heads" on one side and "Tails" on the other.

She ruffled Kanao's hair softly, then placed the coin in her hand.

"Kanao, if you ever find yourself stuck and don't know what to do, try flipping this. Let fate help you decide."

Kanae smiled, her voice filled with affection.

"This trick? A friend taught it to me a while ago. I think it'll be perfect for you."

Kanao looked down at the coin, then up at Kanae. After a moment's pause, she nodded.

"Mm."

Kanae couldn't resist pulling her into a hug and rubbing her cheek against Kanao's head.

"I knew it. You're just the cutest thing ever~~!"

Shinobu, watching this from the side, covered her face. Her sister was at it again—hugging and rubbing faces like some weird affection monster.

Honestly, Shinobu sometimes wondered if Kanae had saved Kanao from that human trafficking ring not out of compassion, but because she'd been completely smitten by her cute face.

Her sister was… hopeless.

Then suddenly, something Kanae said earlier clicked in Shinobu's mind. She raised an eyebrow and asked curiously:

"Hey, that friend you mentioned… who was it? Another Hashira? Or was it the 'Master'?"

Given Kanae's personality, Shinobu figured it had to be the Master—the kind, soft-spoken leader of the Demon Slayer Corps. He seemed like the kind of person who'd listen to Kanae's worries and offer comforting advice.

Kanae stiffened slightly, her smile faltering.

"Ah… well…"

Her eyes darted away.

The truth was, after their parents were killed by demons, Shinobu developed a deep hatred for them. If she ever found out that Kanae had been talking with a demon—possibly even befriending one—there'd be hell to pay.

So… Kanae decided to play dumb.

Shinobu narrowed her eyes. "You're acting suspicious…"

Then, as if a light bulb flicked on, she blushed suddenly and changed the subject with almost aggressive speed:

"A-Anyway! Kanao, help me wash the dishes. And oh—your soup spilled on your clothes. Take it off so I can wash it. After that, we'll go take a bath."

As Shinobu whisked Kanao away, Kanae stood in the quiet room, her hand lightly touching her flushed cheek.

"She… misunderstood, didn't she?"

Kanae sighed and smiled to herself.

"She probably thinks I've got a boyfriend now. Geez…"

Still chuckling, she glanced back down at her notebook, ready to pick up where she left off.

And that's when she saw it.

Words were slowly beginning to form on the page—appearing as if someone was writing from the other side.

It was a message from Ryo: [Wanna meet in person?]

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