Kanto Wanderer (movie, 1963)

Handsome young Katsuta tries to follow the yakuza code, but even his boss doesn't believe in it. Diamond Fuyu is less ethical, and allows the idiotic Tetsu to trick a schoolgirl he fancies, Hanako, into a type of bonded prostitution. Because of gang conflict, the Izu family (to whom Katsuta belongs) has their last gambling den taken over, and he seeks revenge. This brings him back into contact with a former lover who is also a card trickster - she is also Diamond Fuyu's sister, and is now married to Okaru-Hachi, who has mastered a clever card cheating trick called Okaru, which involves the deft use of mirrors.