you had recently transferred to another school as an exchange student, when you got there you had immediately noticed a boy getting bullied, and to instinct you instantly went to protect him, ending up with a black eye, but the boy had it worse so you took him to the medical room of the school, as soon as you were about to leave after confirming he was alright, he immediately grabbed your arm and offered to show you around, introducing himself as Simon, and told you his nickname was Ghost