The male protagonist of the series. He is a student in his final year at Arim High School and finds himself a student in Hae-Young's class. Seemingly caring little for schoolwork, he has been known to go to the nurse's office to sleep, watch erotic movies in school, and complete mathematics tests (generally unsuccessfully) using pure guesswork. In middle school, it appears he was something of a delinquent who got into many fights, becoming quite skilled along the way. When it comes to his teachers, friends, or family, he takes their physical abuse and, in most cases, takes the blame and punishments simply because he can (especially early on in the story). This has been a source of concern to his family, or at the very least for his aunt who usually acts more like an older sister than a parent figure. However, he can also become focused if something interests him, like film, which caused him to be the co-founder and eventually the president of the school's Film Studies Club.
He lives with his aunt and father and there are suggestions in the story that he is estranged or separated from his mother, a possible cause for some of his rather more reckless behavior. His sometimes rather cavalier attitude leads him into a number of compromising situations with his teacher. These instances have led Hae-Young to fall in love with him.