Keiko is a divorced single mother in her mid-forties, who lives a good, normal life with a stable job. That is, until she catches her only daughter, Mayu, having sex with her girlfriend, Saori. She pretends she hadn't seen them, but she can't help but see Saori in a different light. While she ponders how to deal with the situation as Mayu's mother, Saori is about to make that decision for her.