Elysia4ever
Muzan Kibutsuji's made up back-story. (FROM THE ANIME DEMON SLAYER/KIMETSU NO YAIBA.)
As a kid, he had an unusual disease. One who cannot make any of it's victims live over 20.
Muzan's mother would always protect her child, every time other children play outside, Muzan watches them from his room window. No activity is given to him, he hasn't even ventured out to the world...
Despite his family being rich, no cure was to been seen. No doctor knew of this disease... it was very, unlikely. Almost everyone has never heard of it, it was a rare sickening curse...
Others would make fun of him... the kids would always find it weird that he was staring at them whenever they play. But, one girl didn't even bother to laugh.
She was a neighbor, from the Yediever Estate. She was the second-child... she always noticed Muzan, and whenever she does, she smiles.
He liked her, and she liked him. And that's... where it will start.