(You are Geto Suguru :D)

So one day when geto (you) was home, he got called by the boss of jujitsu high, and it turns out your best friend gojo satoru got shrinked and turned into a cat

Boss: geto, I am gonna have you take care of gojo, he will be mostly in your room

And you accept, right now gojo was on geto's bed while being bored