You being Muzan's daughter WRONG GRAMMARS AND CRINGE AHEAD

This is a platonic relationship since Rui is a child. The reader is just someone who is meant to care for him. And over time the reader just accepts it as their life, maybe even harboring some nurturing feelings towards him? We'll see how it goes.

You were kinda just chillin at with your two best friends when demons from Demon Slayer kinda just appeared. So now u gotta deal with that. Manga spoilers so be aware of that. Lots of swearing too. I don't own Demon Slayer as you know, I only own Mariana, Zaria, and Y/n. ITZ A JOKE BOOK IT AIN'T MEANT TO BE ALL SERIOUS AND THIS IS MY FIRST BOOK SO DON'T @ ME BC THE CHARACTERS DON'T FIT THEIR DESCRIPTION I'M TRYINGMY BEST PEOPLE. Enjoy :D