"It's delicious..."
Shinobu sipped the miso soup with a displeased expression and mumbled those words in a daze.
"It is delicious!"
"If it's good, that's enough."
I nodded as I watched the two of them eat heartily.
Shinobu pouted, her lower lip jutting out as if something was bothering her.
"That's not fair! We're demons, and it's tastier than mine!"
It was a childish complaint born from feeling defeated.
Although it was a trivial grumble, seeing them like that was better from my point of view.
It was more comforting to watch them behave like children their own age than to pretend to be unfazed like grown-ups with a bold front.
I had intended to feed them breakfast and send them home right away...
But they absolutely refused to go back.
What a headache.
And just like that, three days had passed.
Kanae and Shinobu never left; while doing odd jobs, they kept asking me about demon hunting, and I kept saying it was impossible.
Before I knew it, my routine had become: come home from work, eat the dinner they made, then in the morning set out breakfast and wake them up.
It was a strange yet somehow fitting combination.
A pair of sisters who'd lost their family to demons and were left alone.
And a demon who'd been abandoned by the very bonds they'd once left behind.
In the sense of being left in the world after sending someone away by force, we were all in the same boat.
It wasn't surprising that I'd grown attached under these circumstances.
So it didn't take long for me to realize they would never give up on demon hunting.
Any talk of protecting their peaceful future would only sound like telling them to run from their past.
If I sent them home, they'd only come back again.
…
The longer I lived with them, the more my judgment seemed to fade.
I clung to that fading sense of reason over the past three days.
Today, as I watched Shinobu cooking rice, I made my decision.
After all, their choice was demon hunting.
Once that idea had dug deep into their hearts, they would never abandon it.
So I decided to entrust these children to the Demon Slayer Corps.
I wasn't even sure if it was the right thing to do...
I'd hoped that after being saved, they could live ordinary lives...
And yet...
It might be better for them to be with the Corps than to stay by the side of a demon like me.
Whether the Corps would accept the sisters was up to them.
In any case, if they couldn't join, they wouldn't be able to hunt demons.
Aside from sunlight and Wisteria flowers, the only weapon capable of killing demons was the [Ichirin-do], which only the Corps could produce.
At least this would be better than encountering a demon by chance later and being torn apart in a fit of rage.
It was an irresponsible thought, but still—better than staying by my side.
So...
"I give up, you brats."
I declared my surrender.
"What do you mean?"
"I'm saying I'll help you become members of the Demon Slayer Corps."
I sighed as I answered.
"Really? You'll really teach us?"
Shinobu's face lit up with joy, the exact opposite of my own expression.
I nodded at her question.
"There are only three weapons that can kill demons."
To keep my promise to teach the sisters how to hunt demons, I stopped eating and held up three fingers.
"Three?"
I nodded at Kanae's questioning look.
"Yes."
I folded down my fingers one by one as I began my explanation.
"As you both know, the first is the sun. Not even I nor Kibutsuji Muzan can overcome it. No matter how powerful a demon is, in the face of sunlight all demons are equal."
"Muzan's goal—his reason for a millennium of folly—has been to overcome the sun. That shows you how absolute sunlight is to demons."
"The second is Wisteria."
I ignored a protest and folded my middle finger to continue.
Wisteria is indeed a poisonous plant. Its seeds and pods are particularly toxic, causing severe vomiting, diarrhea, and dizziness if ingested.
But the flower is different. Though it contains toxins, they're far less concentrated, to the point where people brew tea with Wisteria blossoms.
For demons, however, the poison in the blossom is lethal.
"So that's why Grandpa used to burn Wisteria flowers at night..."
"Right. By burning Wisteria blossoms, you can effectively keep demons at bay."
The poison in the Wisteria's fragrance is strong enough to repel most lesser demons completely.
Of course, the Twelve Kizuki are a different story.
Finally, I folded my index finger.
"The third is the [Ichirin-do]."
I pulled the [Ichirin-do] halfway from its scabbard to show them.
The blade glowed a pale violet, like Wisteria blossoms, exuding a sharp aura.
"Wow... a pale violet sword..."
The sisters stared in wonder at the [Ichirin-do]'s blade.
"So cool! No way I'm lending it!"
I slid the [Ichirin-do] back into its scabbard, leaving a disappointed Kanae and a puffed-up Shinobu behind me.
Seeing Shinobu's expressive face made me laugh before I knew it.
That girl sure is fun to tease.
Turning away from Shinobu's catlike hiss, I continued.
"The [Ichirin-do] is forged from jet-black steel tempered in sunlight. Because it's infused with the sun's power, it burns demons—behead one with it, and the demon dies."
That concluded my lecture on the third method of killing demons.
"Any questions?"
I brought a piece of smoked meat to my lips as I spoke.
Kanae shot her hand up eagerly.
"But demons are strong, right? If you swing the [Ichirin-do] and don't manage to cut off its head, wouldn't it be useless?"
"Yes, and Mr. Himejima moved incredibly fast, too."
Mr. Himejima? Is that the name of the Stone Hashira?
Anyway.
"Exactly—that's why what you need is [Total Concentration Breathing]."
"Total Concentration Breathing?"
"It's a special breathing technique that turns your body into a superhuman. The Demon Slayer Corps uses this breathing while wielding the [Ichirin-do] to decapitate demons."
"So that's what you're going to teach us—[Total Concentration Breathing]?"
I shook my head at her.
"No."
Shinobu voiced a faint complaint.
"But aren't you going to teach it?"
"Because I don't know which breathing style best suits either of you."
"Breathing... aptitude?"
There are five original schools of Breathing—thunder, flame, [Water Breathing], rock, and wind—derived styles like [Mist Breathing], flower, and [Moon Breathing], and even the original [Sun Breathing].
The effects vary wildly depending on one's aptitude.
Usually instructors teach [Water Breathing] since it's the least taxing and easiest to learn, or they teach their own style.
But [Moon Breathing] is different. Like [Sun Breathing], no one outside the chosen has ever mastered it properly.
So I can't teach you that style. I know the theory, but it's better learned from an authorized instructor.
"So there's nothing we can learn here..."
Shinobu said, disappointed.
I had told them: staying here won't get you what you want.
I never lied.