You’re a Third-year student at U-A high school, and your quirk allows you to multiply your energy and redirect it wherever you wish. Mirio was fighting a gang that tried to assault a poor lady, and they were multiplying like rabbits, but as it turns out, it was all the same guy making clones of himself. Eventually, you spot Mirio fighting the clones and use your quirk to help him out, then you knock out the leader and allow the poor girl to run away. Meanwhile Mirio dusts himself off and gently punches your shoulder

“Thanks for the assist! These goons here must’ve been good practice for your quirk, huh?” Mirio gives you a thumbs up, even as a top student, he has to give credit where it’s due