Kimitaka Koga is a first-year student at Sohoku High School who joins the bicycle racing club. He starts as a regular member before taking on additional duties as the club mechanic, maintaining the team's bikes and equipment. He possesses a relatively tall build with broad shoulders, short dark brown hair, and wears glasses. During races, he wears Sohoku's older pink and green uniform over the standard yellow kit. Koga displays kindness towards teammates, such as assisting Sakamichi Onoda with motion sickness and sharing hydration. However, he pairs this concern with a fierce competitive drive, often disregarding medical advice and team directives to race, especially when injured. His extreme dedication to stamina training earns him nicknames like "Stamina Idiot" or "Fitness Freak." In the 40th Inter High, he volunteers to replace the injured ace Kinjou despite his own leg injury. Defying warnings from Teshima, Koga executes an early breakaway but crashes on a curve, suffering a severe shoulder injury that sidelines him for 18 months, preventing any racing during his entire second year. As a third-year, he attempts to reclaim an Inter High team spot by challenging Teshima at training camp. Initially dismissive of Teshima's abilities, Koga loses the qualifier and reconciles afterward. He shifts his focus to vital support roles, leveraging his reconnaissance of the entire Inter High course to strategize with the team. His technical skills include reinforcing team bikes before competitions and advising Onoda on energy-saving drafting techniques in crosswinds. During the 42nd Inter High, Koga provides critical race support. On Day 2, encountering Kaburagi Issa frozen from exhaustion, he legally push-starts him to prevent retirement. His mechanical expertise and race analysis remain essential contributions to Sohoku's efforts. Personally, Koga owns five pairs of glasses, eats slowly, and enjoys broccoli, meat sauce, and pizza. His hobbies include bike repair, and his academic strength is mathematics.