Cross Game follows Kou Kitamura and Aoba Tsukishima, two teenagers from neighboring families whose lives have been intertwined for years through friendship and business. Kou is the only child of the owners of Kitamura Sports, while Aoba grows up at the Tsukishima family's batting center, and the two households move through each other's homes like an extended family. Even so, Kou and Aoba rarely agree on anything. Kou acts indifferent to baseball, yet years spent around the batting cages have quietly made him a natural hitter; Aoba lives for the game and has the form and talent of a gifted pitcher from an early age.
Their rivalry is tied just as strongly to Wakaba Tsukishima, Aoba's older sister, whose warmth keeps the families closely linked and whose bond with Kou becomes a source of jealousy and emotional tension for Aoba. As Kou and Aoba trade barbs, compete, and test each other's pride, baseball becomes the arena where stubbornness, affection, and unspoken feelings shape their growth. Cross Game builds its drama from small rivalries, private hopes, and the pressure of living up to relationships that seemed decided long before either of them understood what they meant, pushing Kou and Aoba toward self-awareness and a connection neither can easily define.