Rin has always been an outsider. Forced to transfer schools often to follow his widowed father, he has never had time to fully settle in anywhere. Short and simple-natured, he is constantly bullied at every new school he attends. However, at one school, through a series of events, he ends up hitting a home run off the talented pitcher, Hayato, in a sandlot game despite not having played baseball before. Shocked yet excited, Hayato makes a promise with Rin to train hard and become Japan's No.1 pitcher and slugger, respectively, so they can play together in the future.