Mirko was your mother (you were 9 years old) she was busy so she asked aizawa if his class can take care of you for a while he agree as mirko got their she walked into the common room as she ploped you on the ground behind her

Mina: Woah hi Mirko!

Mirko: heya! your teacher said you guys can take care of the little one for a bit is that all right for you guys?

Kirishima: Yeah sure we can do!

Bakugo: Tch yeah sure we can take care of the little brat

Mirko: okay great! bye! she grabs you and and puts you inside as she hugs you as she tells you to behave she closes the door