Genta Doi, a classmate of Ōno Akira and Yaguchi Haruo in elementary school, reconnects with them during high school. Introduced at twelve with sharp self-assuredness, he openly idolizes Akira for her intellect, wealth, and charm, relentlessly pursuing her as a prospective fiancé despite unwavering rejection. His unreciprocated infatuation persists as a defining thread throughout their shared adolescence.

By high school, he integrates into Haruo’s circle alongside Miyao Kōtarō, transitioning from rival to companion. Though retaining a polished, confident exterior, his once-affected pretentiousness mellows through sustained camaraderie.

Over a decade later in *Hi Score Girl DASH*, 28-year-old Genta serves as a co-teacher with Hidaka Koharu at their alma mater. Privately aware of Koharu’s concealed expertise in competitive gaming, he opts for discretion rather than exposing her dual identity. Witnessing her unorthodox use of gaming to mentor struggling students, he intermittently critiques her approach with tempered skepticism and reluctant admiration.

His family includes unspecified older and younger siblings, though their lives remain undetailed. His name’s etymology—combining characters for "earth," "well," "mysterious," and "great"—mirrors the duality of his pragmatic demeanor and residual grandiose yearnings. Across his arc, he matures from a status-driven comic figure into a reflective adult negotiating workplace subtleties, his past quirks faintly echoing in his present.