The Unforgiven (2005)

Tae Jung and Seung Young are old junior high classmates. They are reunited when they are assigned to the same army base for their military duty. While Tae Jung is a sergeant near the end of his army service, Seung Young enters later as a private and has a hard time adjusting to army life, which is all about orders and obedience. Tae Jung, in a position of authority, is able to make Seung Young's life easier, but even after time passes, Seung Young is still unable to adjust to the army routine and he becomes more and more isolated from his fellow soldiers. Even Tae Jung is constantly put in awkward situations because of him. Then, after Tae Jung has been discharged, Seung Young slowly starts to change... Later, while out on leave, Seung Young asks to meet with Tae Jung. However, Tae Jung seems to feel uncomfortable around him...