Incidental Murders (1961)

The daughter of the wealthy Soga family is kidnapped and her fiance is murdered. But the kidnappers, Tatsu and Sanko are unaware that Tatsuko is the heiress to a fortune. Two strong-arm brothers, Kosaka and Takeshi, learn of her identity and join the gang in an effort to shake down the tycoon for ten million yen. Upon joining forces, their first move is to rid themselves of the driver whose identity is known to the police because of a cap which he left behind at the scene of the crime. Upon obtaining the ransom money, the brothers murder the two kidnappers and go to the port city of Kobe. The younger brother, Takeshi, has fallen in love with the prisoner and refuses to allow her to be killed and they take her with them from one hideout to another.