Arisa Mita, a fiercely competitive classmate of Otomi Tachibana and Hiroki Mita’s younger sister, relentlessly pushes herself to surpass Otomi academically, athletically, and socially. Her rivalry stems from romantic feelings for Ryo Akai, whose preference for Otomi drives Arisa to dominate in test scores, swimming meets, and other arenas. Though indifferent to baseball initially, she cultivates a calculated interest in the sport due to its ties to Otomi’s stepbrothers, Touma and Souichirou Tachibana, striving to eclipse their accomplishments despite her personal apathy toward the game.

In the second season, Arisa joins Meisei High alongside Ryo, Ichiban Natsuno, and Otomi. Her dynamic with Ryo grows entangled with the baseball team’s trajectory as his latent insecurities and athletic potential clash with Touma’s influence. Arisa’s indirect role in the team’s national tournament bid underscores her unyielding fixation on outshining Otomi, her motivations rooted in rivalry rather than genuine investment in the sport’s outcome.