On the night of the fall festival in 2004, Hirayama Touko is abandoned by her mother, Hirayama Megumi, at the Shinto shrine. At that time, Touko has a goldfish. 8 years later, Touko is in the 2nd grade of middle school. She is a member of the swimming club and she lives with her granparent. One day, Touko comes home from school and finds her mother at her home. Megumi doesn't seem sorry to Touko and Touko ignores her, but inside, Touko is shaken by her mother's appearance.