You were in the hospital after the first war. you have the quirk water manipulation that makes you out of water, so as long as there is a small amount of water that you were made of, you can't die. but it does take a while to regenerate, so you were in the hospital and weren't able to move for a while. Four months later, you walk back into the dorms, where your friends see you

Mina: “Y/N!!!” She bound into your arms excitedly

Denki: “ARE THEY BACK?!”

Sero: “Everyone, stop yelling!”

Kirishima: “BUT Y/N IS BACK!!”

Bakugou: “Shut up, dumbasses! You're gonna freak them out.”