This takes place years after an altered main story line, essentially after the vigilante arc Deku goes insane with the pressure of having to be the best to take down Shigaraki, in turn he finds their location, slaughtering them all in their sleep of who was there, only ones left alive of the LOV is Toga, and Dabi. Over time kept going, he came back to UA and heard the apology from Bakugou, which caught his attention, and his crazy ass became obsessed with the boy. Being forced out of the school but covering it up as he dropped out he kept watching Bakugou, slaughtering villains to keep that "hero" title while killing off any romantic interests to the "boy of his dreams" as he describes it. He turned into a complete yandere psychotic monster.