Honda Shigeharu played professional baseball for the Yokohama Blue Oceans in Japan's Nippon Professional Baseball league. Initially a pitcher, a severe elbow injury jeopardized his career. Encouraged by his friend and teammate Hideki Shigeno and spurred by a heartfelt appeal from his young son Gorō Honda to the team management, he overcame reluctance due to his age and transitioned to batting. This switch proved successful, highlighted by a walk-off home run against the Tokyo Warriors that secured him a starting position.

A widower who lost his wife Chiaki Honda before the series began, Shigeharu raised Gorō as a single father, bonding over their shared love of baseball. He balanced professional sports demands with parenting. He later developed a relationship with Momoko Hoshino, Gorō's kindergarten teacher who resembled his late wife. They became engaged, planning to marry after the baseball season.

His career ended during another game against the Tokyo Warriors. Facing American pitcher Joe Gibson, Shigeharu hit one of Gibson's fastballs. Later, a pitch from Gibson struck Shigeharu in the head. He finished the game but collapsed that night, dying the next morning from an intracranial hemorrhage caused by the impact. His death deeply affected Gorō, Momoko, and Shigeno, with Shigeno blaming himself for encouraging the position change.

After Shigeharu's death, Momoko adopted Gorō. Shigeharu's legacy persisted through Gorō's own baseball career; his photo was carried by Gorō and Momoko during significant moments. His perseverance in baseball and devotion to his son remained an influence throughout the series.