Shigeno Daigo is an elementary school student whose father, Goro, is a professional baseball player. Inspired by his father, who was once a Major League player, Daigo started playing baseball with the Mifune Dolphins, a youth league team. He was unable to live up to the expectations of being the son of a professional, however, and quit baseball after less than a year. Then, in the spring of his sixth-grade year, Daigo's school welcomes a transfer student who's just returned from America. The transfer student is Sato Hikaru, and it turns out his father is Sato Toshiya, a former Major League player and Goro's close friend. The fate of these two young men begins to move forward!