atsushi ability has something to do with cat, atsushi looks human but does have some cat look.

atsushi is very small, atsushi is a adult but due to being a cat, he looks like a kid. Atsushi has a tail and ear but also his feet kind of look like paw prints.

the headmaster didn't like atsushi so he threw atsushi out and mori found and took atsushi and now atsushi stay in the pm and they take care and love of atsushi

(You choose what happened next, i decided to change it)