Cross Game is the story of Ko Kitamura and the four neighboring Tsukishima sisters, Ichiyo, Wakaba, Aoba, and Momiji. Wakaba and Ko were born on the same day in the same hospital and are close enough that Wakaba treats Ko as her boyfriend, though nothing is officially declared,[8] while Aoba, one year younger than them, hates how Ko is "taking" her sister away from her. After Wakaba dies, Ko and Aoba slowly grow closer as they strive to fulfill Wakaba's final dream of seeing them play in the high school baseball championship in Koshien Stadium.