Joji, originally named Hangorou Ouse in the Japanese version, functions as a supporting character within the racing team narrative. He is the younger brother of Suzuko Ouse, and together they operate as a sibling team for Katori Motors. Their parents run the garage that shelters the protagonist during his recovery and return to racing. Despite his youth, Joji displays notable technical aptitude with extensive knowledge of vehicles and mechanics, serving as a capable team assistant who contributes to car maintenance and race preparations. He exhibits enthusiastic support for the protagonist through admiration and loyalty, consistently appearing during races and team activities to cheer from the sidelines and offer encouragement during setbacks. His relationship with Suzuko centers on their shared dedication to motorsports and collaborative work environment, with their mutual passion cementing their roles as reliable Katori Motors support crew members. Joji maintains this supportive function throughout the series and related media without significant character development, backstory expansion, or involvement in narrative arcs beyond this scope.