Chikan Densha: Yawarakai Hada (1990)

Yasuo, who loves molestation, has a girlfriend named Yoko. When Yoko visits Yasuo's apartment, Yasuo's cousin Sasaki brings his girlfriend Megumi and asks Yoko to look after her for the time being. Sasaki, an elite businessman, is being encouraged to marry Miyo, the daughter of the president of a company that Yasuo does business with. When Megumi starts living in the same room as Yasuo, Yoko, feeling betrayed, starts dating Section Chief Okubo. Thus, the three couples are faced with a series of intense love conflicts...