In the summer before Ren Mihashi makes his high school baseball debut, another drama is playing out at Musashino High. The short-statured Naoto Kaguyama feels threatened by freshman pitcher Motoki Haruna after seeing how seriously he trains. Afraid that Haruna will take his place on the mound, Kaguyama tries to understand why such a devoted player came to their low-ranked school, and how to build their team into one more befitting of a player of Haruna's skill.