Kōhei Kokubo is a young male character with blonde hair reaching his neck and distinctive orange eyes. His physical design includes notably thick thighs. Born in Japan, he formed a close childhood friendship with Hideto Tsuji, playing soccer together until junior high. He then moved to England for study, separating him from Tsuji. Upon returning to Japan, he enrolled at Nomada High School and joined its soccer team, placing him in direct athletic competition against Tsuji, who attends Kakegawa High School.

Early depictions present him as energetic and expressive, yet reveal significant emotional complexity and unresolved personal trauma recurring within the narrative. His motivations center intensely on reigniting his soccer partnership with Tsuji. He persistently urges Tsuji to return to competitive play, a drive that manifests in tearful appeals and verbal exhortations for Tsuji to "shoot" during matches.

His playing style emphasizes technical skill and emotional expressiveness. Entering a decisive match against Tsuji's team as a substitute, he demonstrates tactical awareness and a fervent desire to restore their past synergy despite Tsuji's reluctance.

The name "Kōhei" (公平) translates to concepts like fairness, justice, or impartiality, while "Kokubo" (小久保) combines characters meaning "small," "long time," and "protect." Official media, including the 2022 anime series, positions him as a supporting character whose arc revolves around reconciling past bonds with present athletic ambitions, navigating personal challenges while striving to reconnect with his childhood friend through soccer.