Doumu Shinjou is the 10-year-old son of a legendary deceased player of the Yomiuri Giants. From his father he inherited a love of baseball and an incredible talent for the sport, although both his mother and his older sister try to get him to give it up.
However, before dying, his father had the time to teach him one last trick- a magic shot. After his mother gives him the glove his father used, Doumu makes that shot in a training session of the Giants and is contracted immediately. With the support of the veteran players of the team, the Giants become unbeatable at home- none of the main batters of the Japanese professional league can overcome his magic shot. However, away games are another matter, as Doumu is just allowed to play at home, in the Tokyo Dome in which his father was consecrated.
New rivals, but also friends (such as Melody Norman, an American girl who disguises herself as a boy because women aren't allowed to play baseball), step up to bat along the way during Doumu's journey. The Giants seem to winning the fight to conquer the league- until the arrival of the mysterious Don Carlos, a Spanish ex-bullfighter who plays for the Hiroshima Toyo Carp, and seems to have a past with Doumu's father. Will Doumu succeed in giving the league to the Giants?

(Source: Wikipedia, edited)