Unhinged (A MHA OC story)

Rei and Kei are both teenage vigilantes. Well, it shouldn't have been that way. Their group was supposed to be a trio but with their best friend and the third and most important person in their trio, a transfer student from the US named Jake Merwen gotten killed by a terrifying incident with the hero involved just stand by and watch, Rei and Kei both vowed to never be heroes, but with Stain, their father figure, disappearing so suddenly when they were 15, leaving them alone, and them being approached by a man looking like a hobo and a rat like man, inviting them to UA after watching them struggling to survive in the hellhole called the underworld (undercity), both Rei and Kei agreed, but what they realized is that it was never as they had suspected, with their father figure killing heroes one by one, and them slowly finding secrets of their pasts, about their parents who had left them when they were younger, invoking the memories that they wished they forget, will they be able to survive in UA, through the struggles?