The manga takes place in Matsuyama City, located in the southwestern Ehime Prefecture on Shikoku Island, during the Showa 40s (1965-1975). The Onda family consists of the older sister Sachiko, a devoted fan of the idol Hiromi Dō; the younger brother Takushi, who struggles with arithmetic; the father Yoshito, a factory worker and Yomiuri Giants baseball enthusiast; the mother Natsuko, who hopes to build a home for the family; and the newest member, a cat named Mii.