Kotaro Miyao, a classmate and steadfast friend to Haruo Yaguchi throughout their middle and high school years, evolves into a brotherly confidant, guiding Haruo through personal challenges with unwavering loyalty. He discreetly prioritizes Haruo’s romantic prospects over his own, exemplified by his restraint in pursuing Akira Ono despite mutual attraction, ensuring his friend’s connections remain uncomplicated. Keenly perceptive, Kotaro detects unspoken emotions, such as Hidaka Koharu’s affection for Haruo, and navigates tense dynamics with calm mediation.

Hailing from a large, unspecified family, he balances arcade gaming enthusiasm with a natural social ease that draws peer admiration, contrasting Haruo’s more introverted tendencies. His adulthood, briefly glimpsed at age 28 in *Hi Score Girl Dash*, hints at enduring loyalty to Haruo, though his career and personal evolution post-adolescence remain unexplored.

Physically, Kotaro sports brown hair, with eye color shifting inconsistently from blue to green across media. His presence anchors Haruo’s circle, offering steady emotional support while shunning the spotlight, his actions consistently reinforcing camaraderie over personal ambition.