Gorō Ōyama steers Meisei High School's baseball team as its coach, a role rooted in his own legacy as the school's former team captain. During his student years alongside Eisuke Tachibana and Keiichi Sawai, he honed the strategic instincts and reverence for tradition that now define his coaching philosophy.

Though he publicly asserts having declined lucrative offers to return to Meisei, this claim may mask a tactical maneuver. Despite a reputation for casual neglect, his sharp baseball intellect surfaces in opponent analysis and player guidance. He recognizes Souichirō Tachibana's untapped potential, urging him toward pitching despite the shadow cast by his stepbrother Touma's entrenched position as ace.

Separated yet undivorced from an aspiring novelist wife, Gorō's personal life intersects with the team through his daughter Haruka, who applies her scouting expertise as manager. His enduring camaraderie with Eisuke fuels late-night drinking sessions that frequently derail family meals, echoing their shared Meisei history.

Gorō's coaching choices consistently account for player vulnerabilities, from anticipating Touma's overuse injuries to balancing the Tachibana brothers' rivalry within team cohesion. While his relaxed manner dominates daily interactions, critical game moments reveal his capacity for intense, targeted mentorship—guiding Meisei through tournament pressures with calculated foresight.