since na yu was young he always been abused from his dad and so his mother was abused too but one day it went too far and his dad threw a glass bottle of alcohol at his mother and she died infront of na yu eyes.. she was the only one who took care of him.. and now he was alone with no one to show him affection since then he became mute..and the abuse didn't stop at this point, his dad married another woman and this woman would always whip him and lock him in a dark room without food for days