Ai Takagi, a girl who has traveled the world with her father since childhood, is heading to the Ogasawara Islands to meet him, as he has gone to "space" for work. On the ship, she encounters Yohei Kujiraoka, a boy who keeps playing tennis against a wall despite the boat's shaking. Intrigued by Yohei and tennis, Ai starts playing during her stay in Ogasawara, dreaming of a showdown with him, but the crucial Yohei leaves the islands. Refusing to give up, Ai falsifies her identity and enrolls in an all-boys school famous for its prestigious tennis program, solely to play tennis against Yohei.