Gyu is a prominent character distinguished by the jewel that replaces his right eye, which is linked to his elemental affinity for flames. His background is rooted in loss; prior to joining the main group led by Kou, he was a member of a rebel faction that disbanded following the assassination of its leader, Don Erume. This event left Gyu without a community, and he subsequently found companionship primarily with Kou and the others, as well as a specific ranch girl.

In terms of personality, Gyu generally presents himself as a nice individual, though he prefers to maintain the facade of a loner. This self-imposed distance is complicated by a deep-seated and persistent hatred within his heart, a darkness he struggles to extinguish. His motivations are initially shaped by this internal conflict, driving much of his behavior throughout the narrative.

As a fighter, Gyu wields a distinctive weapon: a scythe attached to the end of a long chain. This, combined with his fire-based powers granted by his jewel eye, defines his notable abilities in combat. Within the story's progression, Gyu undergoes significant development. His journey leads him to a crucial turning point where he learns an important lesson concerning life, death, and the nature of friendship. This evolution is central to his role, allowing him to confront and ultimately move beyond the hatred that had long defined him. His key relationships, particularly with Kou and the girl from the ranch, serve as anchors that challenge his loner persona and facilitate his personal growth.