17-year-old Won-Deuk (Yoo Ah-In) is a sophomore in high school with a miserable outlook on life. He doesn't have much interest in school, his diminutive size father has a hunchback and Won-Deuk doesn't know anything about his mother. The one thing that Won-Deuk excels at is fighting. Although he isn't aggressive by nature, If anybody makes a snide comment about his father then Won-Deuk has no problems beating the crap out of them. Making Won-Deuk's life that much more miserable is his homeroom teacher Dong-Joo (Kim Yun-Seok) who seems to frequently pick on him in class. This bothers Won-Deuk enough that he often prays in ch11urch for Dong-Joo's sudden death. If Won-Deuk doesn't get enough of his homeroom teacher at school then he often sees him at home. Dong-Joo lives in a rooftop apartment directly adjacent to Won-Deuk's rooftop apartment.
One day, his homeroom teacher unveils a bombshell on Won-Deuk. He tells him that his mother is still alive. In fact, his mother is a Filipino woman who immigrated to Korea and lives not very far from him. Furthermore, Dong-Joo tells him that his mother would like to meet him. Won-Deuk is stunned and confused.
A few days later, Dong-Joo discovers the car belonging to Won-Deuk's father has been vandalized. Dong-Joo knows immediately that the man that lives in the apartment directly in front of the parked car did it. Dong-Joo yells at the man from the street to come out and then demands an apology. Instead of apologizing the neighbor curses at Won-Deuk's father. Before anybody can do anything, Won-Deuk punches the neighbor in the face. They all go to the police station.
At the police station, Dong-Joo stands up for Won-Deuk and attempts to shield him for any type of punishment. The neighbor is still persistant in getting charges filed, but his sister Ho-Jung (Park Hyo-Joo) apologizes for her brother's behavior and brings the matter to a close. Meanwhile, homeroom teacher Dong-Joo becomes attracted to his neighbor's sister. Won-Deuk also begins to view his homeroom teacher in a different light.