Kou Kitamura is a fifth grader whose family owns a sporting goods store. A regular customer of his family's shop is the Tsukishima Batting Center, which allows him to become very familiar with the four daughters of the Tsukishima family: Ichiyo, Wakaba, Aoba, and Momiji. Because Kou has spent so much time practicing in their batting cages, he has become a genius hitter, though he lacks knowledge of any other aspect of baseball. This contrasts with Aoba, who, despite being a year younger, is an adept pitcher and hitter. Wakaba is Kou's classmate, and she seems fully intent on marrying him when she grows up. Everything appears idyllic in their world until tragedy strikes. The story then jumps forward four years. Kou has continued the training he began four years ago but has not played in a baseball game since. As he finally starts playing again, it remains to be seen whether he will live up to the expectations of those who know the true talent he has been hiding all this time.