Mami, the third daughter of the Asaoka family, is a first-year high school student with big dreams. She attends a missionary school for girls. She has an older sister, Asako, who graduated from college and works as a secretary at a small company, a second sister, Mie, a modern girl who dreams of becoming an actress, and a younger brother, Kenichi. The Asaoka family, consisting of a mother who raises four children on her own, is a close-knit and peaceful family. A handsome young man named Shiro Koizumi moves into the Asaoka family's neighborhood. His presence touches the hearts of her sisters, and through them, she understands the meaning of love and youth.