Miyoko Tabuchi is the wife of professional baseball player Koichi Tabuchi, the series' main character. Her portrayal is a direct adaptation of the real-life spouse of the athlete who inspired the series. She provides crucial emotional support to her husband throughout his career challenges and periods of depression.

During a pivotal moment of Koichi's performance struggles, Miyoko arrives at the baseball stadium dressed as a cheerleader to revitalize his spirits. This act mirrors the real-life event in which the original manga enabled the athlete to meet his actual wife, further cementing Miyoko's narrative role as his emotional anchor.

Her supportive presence continues as a consistent figure in Koichi's journey across the entire film series, including the third installment.