Tall young man with messy black hair and glasses, he is almost always seen wearing a school uniform. in the hospital where he meets the detective, Kyungjoon is wearing mostly blue clothing.
He has an inferiority complex and a very sadistic nature as he made jungho put a cigarette out on his tongue (refer to the prologue).
After Jungho defeated him, his personality shifted, he became slightly more forgiving. (refer to episode 13, where he was defeated)