In a world where baseball has become the dominant global sport and nearly every person on the planet plays, the story follows a transfer student named Towa Shima Misuta who suddenly appears at Tokyo Dome Elementary School. This is an age where 8 billion people are baseball players, and the sport is treated as the ultimate measure of ability and status. Towa quickly becomes a central figure, clashing with powerful rival players and teams in intense youth baseball competitions.

The main character is Towa, a prodigy with an extraordinary talent for the game. He is joined by key teammates such as the team’s ace pitcher Nami, whose past life as a professional athlete from another sport is hinted at, and other members of the Tokyo (Tōkyō) selection squad. Their opponents include top players from other sports—boxing, soccer, golf, bowling—who have crossed over into baseball, bringing their unique skills to the diamond. The narrative focuses on the selection matches between Tokyo and the rival team from Zero Hanshin (Rei Han), led by a tactical opponent named Noshin. During one critical game, Towa devises a boxing-inspired batting technique to break the opponent's strong pitching. The climax of the story involves the appearance of the first president of the World Baseball Federation, a legendary figure named Ōya Shōbe, who takes the mound in the final showdown.

Along the way, the series explores themes of reincarnation and past lives, as several characters experience awakenings that reveal their former identities in other sports or even previous incarnations. The story builds toward the Tokyo selection team’s fight to overcome increasingly powerful foes and culminates in a decisive match that determines the future of youth baseball in this baseball-obsessed world. The manga concludes with the resolution of that final game, tying together the threads of rivalry, friendship, and the pure love of the sport.