Debauchery: Salome's Lips (1984)

A female college student who would have ended up in an ordinary life, ordinary sex, and eventually an ordinary marriage is drawn into an unusual sexual experience by chance. She's a private tutor who intervenes between a son and his mother. This strange love triangle creates a skewed sexual relationship. Nikkatsu depicts the subtleties of female psychology, which sways subtly in such a perverted world.