Michiko and Yoshiko would seduce men on the train, rape them, and then use that to extort money from them. Kitajima has not been able to forget Michiko since he raped her. Yoshiko is Michiko's younger sister, but she has not yet known a man and adores Michiko as a lover. One day, an unexpected incident occurs when Michiko steals an unreleased floppy disk from a middle-aged man...