Fainaru faito - Saigo no ichigeki (1989)

Masahiro Kai has made it to the finals of the Free Fighting Championship. In flashback, he remembers training Ryu Tenmei for the event. Ryu makes it to the final bout against the reigning champ, Chang Lee. After Lee kills Ryu, Kai sinks into alcoholism, tangling with a gang of Americans, until he decides to go back into training and defeat Chang Lee himself.