Bondage Nymphomaniac(1980)

Toshihiko, a university student, meets a married woman named Chizuko. Chizuko's husband is a pervert who ties her up and tortures her with cruel techniques. Chizuko, who is used to this abnormality, learns true pleasure when Toshihiko embraces her in the missionary position, and the two begin to live in an adulterous love...