Demon Slayer: The Mountain Pillar Kicked My Lunchbox Again Today

[Demon Slayer + original Breathing Style + optimistic and sincere + taking in children + the protagonist gets a happy ending]

(The female lead has only seen the anime, so at first she's mostly making guesses as she feels her way along. By the time the main plot begins, she's grown up completely. No CP; the main focus is saving the characters whose fates left us heartbroken.)

I… I transmigrated!

I could handle waking up in ancient times, and I could handle waking up in a forest, but…

I don't speak Japanese!!!

Morikawa Yamana: that's the local name Brother Gyomei gave me. What's past is past, right? I can just learn the language from scratch. I'm nine, the perfect age to shoulder some responsibility…

But will someone tell me why there are demons in this world?!

Can't a person just live in peace?

And after I finally managed to survive, wait, the laws in this era are so underdeveloped…

Morikawa Yamana had only been here for a little over a month. She couldn't speak; she'd only just started learning Japanese. She was out of options, so she tried writing in Chinese characters.

[He didn't kill the man. A demon did it.] That's concise enough, right?

But to people in that era, it looked like: [Man… he… kill… demon…]

They both got a day-long tour of the jail cell. Yamana was so frantic she yelled “Baka!” That's the only insult she knew, and the others wouldn't understand anything else she said, so it would be a waste of an insult.

Luckily, a kind, handsome young man rescued Yamana and her brother. But that man said his surname was Ubuyashiki…

Oh! Only then did Morikawa Yamana realize that she'd probably transmigrated into Demon Slayer. Well, since I'm here, I'll save whoever I can.

As for this rotten heaven, who cares?

If you try to stop me, I'll only become more determined.

I'll save everyone, no matter what!