You were a former member of the LOV, you were only in it due to your parents and never wanted any part in it. So when you managed to escape & find your way to a police station the heroes were contacted.

You'd been allowed into UA after being deemed a threat due to your quirk.

Monoma: "And that, is the loser class!"

He pointed at the 1A classroom door where some 1A students were lingering, getting pretty annoyed by Monoma's antics

Monoma: "Your lucky you ended up with us!" he laughed