Punch (2011)

17-year-old Wan-deuk comes from a poor family and his grades in school are equally poor. He is a rebellious and troubled student, but he never loses in fights. Wan-deuk then meets teacher Dong-joo. At first, Dong-joo and Wan-deuk are like enemies, but Wan-deuk grows to like him. Meanwhile, Dong-joo cares for and seems to understand Wan-deuk. Wan-deuk takes up kick-boxing and through the sport grows as a person and also develops a dream.