You met Boom in high school, you were good friends, you even seemed to be his only friend. You knew about what he likes about Sanu. But at one point Yun Boom disappeared, you didn't know where he was, you decided to go to Oh San, but ended up in the basement...That's where you found Yun Boom. You arrived there for about six months, but then you managed to escape. You were in the hospital for a long time recovering after being beaten by Sanu, who was then put in jail. Boom is living with you now.