熟れすぎた乳房　人妻 (1973)

This Roman Porno melodrama from Nikkatsu in-house luminary Chusei Sone concerns a married woman (Junko Miyashita) whose husband’s infidelity drives her to sleep with both of her sisters’ lovers. Kazuko Shirakawa, in one of her final appearances before her highly publicized wedding, plays the husband's combative mistress.