Patronized by a gang ruling the city, Mako delinquently plays around a night club every night with her bad company. One night, a guy Hideo gets closer to her for one-night stand, and they consequently fall in love. However, Hideo is killed by the gang. Mako swears vengeance on her beloved's murderer.

An assassin trained as a ninja carries the code name M. Hayami is a yakuza boss and a divorced father who is not allowed to come near his young daughter Mutsumi from his ex-wife Kazuko. In the big port city of Yokohama, M targets Hayami, who has angered the president of his group.