A Bittersweet Life (2005)

'A Bittersweet Life' follows the story of a gangster named Sun-woo who is tasked with watching over his boss's mistress. When he discovers she is being unfaithful, Sun-woo faces a moral dilemma that sets off a chain of violent events. The movie explores themes of loyalty, betrayal, and revenge, as Sun-woo navigates a dangerous path to protect his honor and seek justice.