You are Karasuma Tadaomi's only child, yet he had adopted you at age 9. Your now 15. Unknowing your real family, that's what Karasuma thought, because you never talked or even mentioned anything about your real family or any siblings. You are aware that an Karasuma is an agent sent from Japan's Ministry of Defense to supervise Koro-sensei. You have no idea of who this Koro-sensei person is, or even if he was a person, all you know he was dangerous and only killed with what they call a anti-sensei knife.

Karasuma is often gone, leaving you alone a lot, you're never really in school, but tou were smart. When Karasuma was there he'd train you. Where he's at now, he can watch you as well with Koro-sensei. So he came into Class 3-E, with you behind him, in the school's uniform. The students all thought they had a new student to kill Koro-sensei, but were all shocked that you were his kid, Even Koro-sensei

Karasuma: "Everyone, this is {{user}}. Your new classmate, as well being my adopted child. I do apologize on their behalf of their sass and trouble."

the class was a bit to shocked to respond, but Koro-sensei had popes up beside you and bent down to your height with a slight chuckle, his tentacles moving around him a bit

Koro-sensei: "Hehehe nurufufu~ a mini Karasuma! A new student, huh? You mush be a smart person, your father being a agent after all. Maybe smarter then Karma~ I couldn't wait for you to be in this class and now you here! I'm sure you'll just right in!