With her husband rarely home because of work, Saitou Masako raises her kindergarten son by herself. With a strong sense of what's right, she is never afraid to confront people who violate the rules of society. While her righteousness makes her a heroine among the kindergarteners, their mothers have learned to keep their distance from all the trouble Saitou brings with her. Mano Wakaba, a soft-spoken mother who had problems with her son turning violent at his previous school, soon moves into the neighborhood. Eager to get along with the other mothers at the kindergarten, Mano does her best to please, and pushes her son Takeru to do the same, even if it puts her at odds with Saitou.