Young Wife: Playful Bondage (1980)

Takao meets a woman with amnesia at a disco. His girlfriend, Miwako, is unhappy when Takao takes her home. Finally, urged by Miwako, Takao tells the woman to leave and goes to university. That night, while drinking with friends, Takao flirts with Kazuki's girlfriend, Yoshiko, ignoring Miwako. The two get drunk and get intimate in Takao's room. The woman with amnesia is still there. Yoshiko gets angry at Takao for continuing regardless and leaves. Seeing Takao leave, the woman says, "You can have me too..." Takao names the woman Akiko. Miwako, who had been putting up with Takao and Akiko's relationship, finally can't take it anymore and attacks Akiko, tying her up with an electrical cord. Akiko's old memories begin to resurface... In fact, Akiko felt an unusual pleasure from being tied up...