Shunichi Minami (Taishi Nakagawa) possesses good looks and does well academically in high school. Chiyomi Horikiri (Maika Yamamoto) is a bright girl who likes dancing. They were childhood friends and also their first loves, but after Shunichi Minami’s father disappeared they hardly talk. On a storming night, Chiyomi Horikiri has an argument with her parents over her future course and leaves home. While trying to avoid the rain, Chiyomi Horikiri wishes that she go back to her childhood. Suddenly, Chiyomi becomes 15 cm. tall. Shunichi Minami happens to see tiny Chiyomi Horikiri. She tells him that she doesn't want anyone else to see her and Shunichi Minami takes her his home.