Mistress.

Shibasaki Kaori is a doctor. Her patient that she was having an affair with dies. Kaori is suspicious of the patient's son Kido Takashi about the death. Noguchi Tomomi is a single mother. She is excited in experiencing love for the first time in 7 years. Harada Saeko is in conflict with her husband Harada Satoshi about having a child. Mizushima Juri insists on having freewheeling romance. She feels excitement with meeting a woman. These four women's lives connect and an unexpected story begins.