In the spring of 1972, twelve-year-old Tomoko leaves her mother behind in Tokyo and boards a train alone for Ashiya, a coastal town in Japan, to stay with her aunt’s family. Tomoko’s aunt is an enigma and an outlier in her working-class family, and her magnificent home and handsome foreign husband, the president of a soft drink company are symbols of that status. The seventeen rooms are filled with German-made furnishings; there are sprawling gardens and even an old zoo where the family’s pygmy hippopotamus resides. The family is just as beguiling as their mansion Tomoko’s dignified and devoted aunt, her German great-aunt, and her dashing, charming uncle, who confidently sits as the family’s patriarch. At the center of the family is Tomoko’s cousin Mina, a precocious, asthmatic girl of thirteen who draws Tomoko into an intoxicating world full of secret crushes and elaborate storytelling.