Fly, Daddy, Fly (2006)

Jang Ga-Pil (Lee Moon-Sik) is an ordinary middle-aged father, who works as a salaryman. One day, he returns home to learn that he his teenage daughter was assaulted by a group of guys at a karaoke bar. The group of thugs is led by box star Kang Tae-Wook, whose father is a powerful congressman. Jang Ga-Pil has little hope of gaining justice due to his modest background. He then concocts a plan to stab the young box star on his way to school. While, Jang Ga-Pil's plan doesn't go according to plan, he meets another high school student named Go Seung-Suk (Lee Joon-Gi). Go Seung-Suk is the only guy to beat Kang Tae-Wook in the boxing ring. Furthermore, he offers to train Jang Ga-Pil so he can get his revenge honorably within the boxing ring.