Kanbara Kiko is a divorcee and raises her 5-year-old son alone. To open a box lunch food store, she moves to her grandfather's house. She tries to enroll her son Haruto into nursery school there, but a person in charge of the district office tells her Haruto can't attend immediately. Kiko, busy to open her box lunch food store by next month, finds herself in a predicament with her son not having supervision by then. At this time, a director of a kindergarten school, Fune Naraoka, talks to Kiko. A month later, on the first day of Haruto attending the kindergarten school, Kiko becomes nervous by seeing all of the luxurious high-end cars that are pulled up in front of the school and the other mothers who are all carrying pricey handbags. The school is a prestigious institution for children. Kiko then sees Kamiya Yuki. They attended the same middle school and high school. Kiko strikes up a conversation with Yuki, but Yuki cuts her off and tells her that the school isn't for common people like her. Among the other mothers there are Yano Satoko, the wife of a doctor, Goto Midori, former career woman and Odadera Marie, who wields the most power among the mothers at the school. They all have their own individual problems that they can't tell anyone.