Demon Slayer : Heir to the Moon

When I opened my eyes, the dream was already fading.

Mother's laughter, Father's laughter…

Gone.

I lay staring at the ceiling of the Butterfly Mansion, warmth pressing in from the sun-drenched window. My body felt… heavy. Not painful like before, but every joint ached like I'd been beaten with a kindness stick. One that hurts, but also leaves tea afterward.

I tried to sit up.

Bad idea.

"Ah—!" I froze halfway, my ribs sending me a very detailed complaint.

Okay. No sudden movements.

A gentle knock came at the door.

A small hand opened it. One of the mansion's little helpers—a girl with pigtails and a clipboard. She walked over without a word and handed me a tiny cup of medicine.

I stared at it.

Thick. Murky. Evil in liquid form.

She smiled, bowed, and left.

"…Coward," I muttered, then drank it.

It tasted like something that had lost a war.

I nearly died again.

But I survived. Somehow.

From outside, came noise. Loud. Shouting. Battle cries?

I pulled myself to my feet like a tired ghost and hobbled to the window.

There they were.

Three boys in the courtyard—sparring, sprinting, falling.

One with bright red hair, sweat pouring down his smiling face. Another in a yellow robe, screaming like he was being murdered by butterflies. And a third… was wearing a boar's head, one who challenged me while I was lying on bed, injured.

Literally.

He was headbutting a tree.

"…Maybe I'm not the injured one," I whispered.

I limped out slowly. The hallways smelled like herbs and polish. The kind of place where even ghosts would be expected to wipe their feet.

I stepped into the light.

And the red-haired one noticed me.

He jogged over immediately, wiping his forehead.

"Hey! You're awake!" he said, smiling like sunrise.

He reached out a hand.

"Tanjiro Kamado."

"…Ryo," I said quietly, shaking it. "Ryo Tsukihara."

He had this… calming presence. Not loud or annoying like the boar man and the screaming chicken. Just warm. Steady. Like a campfire that never flickers.

Tanjiro sat beside me on a bench under the shade.

"What kind of demon did you fight?" he asked, gently.

I took a breath.

"A demon who used illusions. Magic shows. Turned a whole crowd into puppets. He could trap people inside cards. Strong. Though I didn't let anybody die, well except one guy."

Tanjiro's eyes widened. "That sounds terrifying. Were you alone?"

"Until Rengoku showed up."

His face lit up again. "You fought with Rengoku-san, the Flame Hashira?"

I nodded. "He saved me. In the end, he's the one who finished it."

Tanjiro shook his head. "You saved those people. And gave Rengoku the chance to fight. That's not weakness."

I blinked. His words sat in my chest like warm tea on a cold day.

"…Thanks."

He smiled, then looked out at the courtyard.

"So what about you?" I asked. "What demon landed you here?"

Tanjiro hesitated a moment.

Then spoke of Rui. Lower Moon Five. A demon who treated family like a game and blood like a web. He didn't go into deep details, but enough.

"Sounds like a nightmare," I said.

He nodded. "But we got through it."

I looked around. "This place… the Butterfly Mansion. It's nice."

Tanjiro grinned. "It's run by the Insect Hashira. Shinobu Kocho."

"Wait," I said. "You mean that scary woman?"

Tanjiro winced. "Yeah… that one."

Suddenly—A hand landed softly on my shoulder.

"Who are you boys talking about?"

Her voice was sweet. Way too sweet.

I didn't turn around.

Because I knew.

Shinobu Kocho.

I was already dead. I started praying in my final moments.

"I was praising you," I said with a shaky smile. "…Demons would be.. scared because of your.. strength."

She leaned down beside me, her smile bright.

"Good to know. Let's check your wounds again."

"Wait—No that's really not necessary—"

Pain. Instant. Sharp.

She pressed exactly where it hurt the most. With grace. On purpose.

Tanjiro looked away, politely pretending this wasn't happening.

"There," Shinobu said with a clap. "Good as new. You'll live."

"...Yay."

"Oh, and Tanjiro," she added. "Teach him Total Concentration: Constant. Might help toughen him up."

She smiled again and walked away.

My soul tried to leave my body.

Tanjiro chuckled. "She's scary, huh?"

"She's… a different type of demon," I whispered.

We sat in silence for a bit.

Then I asked, "What's Total Concentration: Constant?"

Tanjiro explained.

"It's our breathing technique. But instead of only using it in battle, we do it all the time. While walking. Sleeping. Eating."

I stared at him. "You're joking."

He shook his head. "Not at all. It builds your stamina. Keeps your body strong."

I tried it right then.

Deep breath. Hold. Exhale.

Blood rushed to my head.

I coughed, choked, and nearly fell sideways.

"I'm going to explode," I muttered. "This is a trap."

Tanjiro laughed gently. "It'll take time. Especially while you're injured. Just focus on rhythm."

We practiced together in the garden, sitting cross-legged in the shade.

I could do maybe two minutes before my lungs protested.

But it was something.

"You'll get there," Tanjiro said kindly. "I couldn't do it either, at first."

I looked back toward the courtyard.

The boar man was now hanging from a tree branch by his ankles, doing sit-ups upside down.

Zenitsu was running in circles yelling, "I don't want to die! I don't want to train!"

"…Do they count as normal people?" I asked.

Tanjiro just smiled. "You get used to it."

That's when I saw her.

A girl—my age maybe—standing quietly by the well. A butterfly resting on her hand. She had dark hair and a butterfly hairpin.

Elegant. Still.

Beautiful.

My cheeks burned.

"Don't," I told myself. "You have Yuki."

"Yuki. Yuki. Yuki," I muttered under my breath like a prayer.

Tanjiro noticed. "Oh, that's Kanao. She's Shinobu's apprentice. Very skilled. Doesn't talk much, but really strong. We passed the entrance exam together."

I nodded. Tried to look away casually. Failed.

Just then, my crow swooped down and perched on a post beside me.

"Ryo! Congratulations! You are promoted! You are now Kanoe rank! Caw!"

"…Thanks," I muttered.

Didn't matter much to me right now.

Tanjiro stood. "You'll be training with us once you recover."

I nodded again.

That night, I sat alone in the corner room, watching the lanterns sway in the wind.

Deep breath. In. Out.

Trying again.

Trying to learn the technique.

Failed.

Later, I sat with a brush in hand, trying to write a letter to Master Junjiro.

Tried.

Keyword: tried.

The ink smudged. The lines bent. My kanji looked like they'd been mugged in an alley and left for dead.

My handwriting was so bad, even I couldn't tell if it said "I'm recovering" or "I am raccoon."

I scratched my head, gave up on the brush, and tried drawing little arrows to fix the sentence. Now it just looked like a cursed seal.

I heard footsteps behind me.

It was Aoi. One of the nurses I guess, well she also does cooking and cleaning, an All-rounder.

She peeked at the paper.

Paused.

Blink.

"…Are you bleeding?"

"No. That's the letter."

She said nothing. Walked away.

I stared down at the mess I created.

My hand writing is not that bad, its readable but my right hand is injured currently.

"…Maybe I'll just ask Tanjiro to write a letter for me."

To Be Continued.