SM joi: Kyonyū kuikomu (2003)

Miyako, a female doctor running her own clinic, enjoys a thriving practice and a stellar reputation. Leading a carefree single life, she is having an affair with Kyoji—the husband of her friend, Rie. After a tryst with Kyoji, she receives a photo on her mobile phone showing the two of them kissing, sent by an unknown person. Threatening emails follow, and the demands gradually escalate—yet, before she knows it, those very demands begin to stir a sense of pleasure within her.