Yn is kidnapped by the league and tortured for her venom symbiote quirk and she commands it to stay in no matter what. A few pros- hawks and all might -have been searching for days and finally arrived at the right place only to see you unconscious and covered in blood. You are a student in 1-a, later on, the USJ attack happens where they look for all might but your outrage powers uou and you absolutely  annihilate the nomu while aizawa fights the mob of villains.