If You Say I'm Old, I'll Knock You Out with One Punch.

Ang Lee traveled through time and became a 65-year-old sick and frail uncle. In order to save his seriously ill granddaughter, he bound to the boxing champion system and regained his uniform. He swept the arena as the "One-Punch Master", defeated conspiracies, defeated powerful enemies, and his body returned to youth. In the end, for the sake of his loved ones and glory, he challenged the strongest in the world and staged a passionate age-reversing legend.