Kotaro Miyao, a classmate and steadfast confidant of Haruo Yaguchi, shares his academic journey from middle school through high school. Serving as a brotherly anchor, Kotaro provides candid guidance on personal struggles and prioritizes Haruo’s happiness over his own unspoken feelings for Akira Ono, deliberately stepping back to avoid disrupting her bond with Haruo. Keenly perceptive, he quickly identifies Hidaka Koharu’s quiet affection for Haruo and silently observes the fragile tensions within their love triangle. His guarded demeanor around Akira and Hidaka reveals an intuitive understanding of the emotional stakes at play.

Years later, in *HiScore Girl DASH*, Kotaro remains a steady presence within the group, now navigating adulthood in his late twenties. He discreetly engineers social opportunities for Hidaka, now a middle school teacher, signaling a lingering protectiveness toward her solitude. While embracing a calmer, more measured role among peers, he maintains ties to his past, balancing adult relationships with enduring loyalty to old friends.

Across his story, Kotaro’s decisions hinge on quiet self-restraint, often sidelining his desires to safeguard the equilibrium of those around him. His family—parents and siblings unnamed—remains a background element, with no elaboration on his life beyond shared arcade memories and group dynamics.