Subaru Hasegawa aspires to be one of the greatest basketball players of all time, but his dreams seem thwarted when his school's basketball team goes on hiatus for a year. Disheartened by this development, he gives up on the game altogether. Things take an unexpected turn when his aunt Mihoshi Takamura invites him to coach the Keishin Academy's girls' basketball team. Though initially hesitant, Subaru agrees to train the team, which includes fifth-graders Tomoka Minato, Maho Misawa, Airi Kashii, Hinata Hakamada, and Saki Nagatsuki, with the goal of defeating all formidable rivals along the way. Ro-Kyu-Bu! chronicles the journey of these five young girls and their coach as they strive to improve their adorable, yet efficient style of playing basketball.