Akio Nitta is a star slugger from Sumi Tech High School, which became the national Koshien tournament runner-up. His serious commitment to baseball was ignited after a middle school game against Kazuya Uesugi, sparking a lasting competitive rivalry. Before dedicating himself to the sport, he experienced a period of delinquency in junior high, where he forged a lasting friendship with Harada. He holds a mild romantic interest in Minami Asakura and has a younger sister named Yuka Nitta. His personality blends confidence and determination with occasional overconfidence on the baseball field. Respected by teammates and displaying leadership, his intense nature fuels his rivalry with Kazuya Uesugi, which stems from childhood encounters where Nitta bullied Kazuya. In the events of Touch 3: Don't Pass Me By, he plays for the Meisei High School baseball team.