13-year-old elementary school student Ki-ho likes his classmate Sang-hee, but Sang-hee is close with Byung-soo and doesn't pay attention to Ki-ho. Feeling suffocated by attending multiple cram schools daily and the nagging of adults, Ki-ho decides to form his beloved baseball team. The children secretly use their allowance to create funds and push for the formation of the baseball team. However, upon learning of this, the principal and parents oppose it, and the children fall into despair. Furthermore, conflict with Byung-soo, who hides his passion for baseball due to parental opposition, breaks the children's unity and makes the relationship between Ki-ho and Sang-hee awkward. But thanks to the warm consideration of Teacher Choi, the children re-form the baseball team and dedicate themselves to practice. Sang-hee, watching Ki-ho's earnest efforts, gradually begins to take an interest in him...