Su-chan, Mai-chan, Sawako-san follows the lives of three women who are former co-workers. 34-year-old Su-chan works at a coffee shop and has feelings for the manager there. 34-year-old Mai-chan works at an OA machine maker. She is in a relationship with a married man. 39-year-old Sawako works as a web designer and also takes care of her grandmother. -san and her mother take care of her grandmother.

Shunsuke Honma is a detective from the #1 investigation team at the Tokyo Metropolitan Police Department. Shunsuke takes a leave from work due to an injury. One day, his relative comes to see him and asks him if he can find his missing fiance Akiko Sekine. Shunsuke takes on the job and enlists the help of Detective Sadao Ikari. The detectives soon uncover the shocking truth behind the missing woman.

A woman named Kazuko (Kimura) who was guilty of a “serious crime” in the past, along with three of her friends. Those friends suddenly begin to die one by one. Kazuko learns that one of those deaths is somehow connected to Mamoru (Nakamura Aoi), her younger brother from whom she has been separated ever since their father disappeared 15 years earlier. Although Mamoru knows nothing of his sister, Kazuko is determined to find the killer in order to protect Mamoru and herself.