Tôru Kamei - Watashi no dorei ni narinasai AKA Be My Slave (2012)

Synopsis:

Dan Mitsu stars as Kana, a female employee at a publishing company who strikes up a sexual relationship with a younger co-worker (Mayama Akihiro). He soon discovers that Kana's fetishes extend to sadomasochistic tendencies, involving a mysterious man only known as "Sensei" (Itao Itsuji). This discovery will push his relationship with Kana to a new, dangerous level that he may not be ready for.

Be My Slave, an edgy erotic drama is based on a popular novel about the secret fetishes of urbanites.