Susumu Karasawa, a former prefectural junior high judo champion, enrolled at Seishu High School. He and his friend Katsuya Niimi witnessed the school baseball team's loss and saw Yuri Nakao crying in the stands. Motivated to make her smile, they joined the struggling team. Karasawa's judo background gave him significant physical strength, translating into a powerful throwing arm as the team's right fielder wearing jersey number 9. Though initially inexperienced in baseball, his athleticism provided a solid foundation for developing baseball skills. He maintained a close friendship with Niimi, often providing comic relief through exaggerated reactions and enthusiastic behavior. His loyalty was evident in supporting Niimi during romantic rivalries involving Yuri and Yukimi Yasuda. A significant early action involved mediating a conflict between teammate Eiji Kurahashi and Kurahashi's disapproving father. Karasawa and Niimi directly intervened, facilitating a reconciliation that allowed Kurahashi to rejoin the team, demonstrating Karasawa's role in resolving conflicts critical to team cohesion. Throughout the series, he remained a consistent presence in the outfield and lineup, contributing to the team's progress. His character development saw him transition from a novice player to a dedicated team member, adapting his judo-derived physicality to baseball demands, while maintaining his supportive role within the team dynamic and fostering unity.