The Rambling Guitarist (1959)

Shinji (Akira Kobayashi), a wandering street musician, gets involved with a mob boss, Akitsu (Nobuo Kaneko), after saving one of his henchmen in a bar fight. Akitsu gives Shinji a job to evict an offshore fishery, but things take an unexpected twist when Shinji finds out the owner's wife is Akitsu's actual sister. As Shinji protects the Akitsu family, Akitsu's daughter takes a romantic interest in him. Shinji's mob life becomes more complicated when a member of the Taguchi family questions if Shinji is an undercover cop.