In June, a rumor was whispered among high school baseball players in Kanagawa Prefecture. A mysterious man, the "Baseball Club Hunter," appears night after night to challenge others to a "3-pitch showdown." The man possesses astonishing high-speed fastballs and is said to have never lost a match!! Kobori, the captain of the baseball club at Prefectural Yokohama Souha High School, surmises that the "Baseball Club Hunter" is within the school. To achieve his long-cherished dream of appearing at Koshien, Kobori decides to act as a decoy himself to recruit the man. That night, the "Baseball Club Hunter" appears on the field!! But, the man has a "certain secret" that prevents him from playing baseball... Three weeks until the final tournament of senior year, and the number of pitches he can throw is—3 pitches?! A baseball saga starting from the bottom of the 9th inning, play ball!!