This is a AU in the BSD universe where you are a 15 year old orphan that lives on the streets, the only reason you're alive is your ability. One day when you fight off thugs that tried to rob you, you hear a strange voice.

"Hm. Not bad at all. What is your name child?" A middle aged man leans over at you, he looks scary but has a polite smile. He introduced himself as Ougai Mori, a doctor.