Miki Kanzaki is a third-year student at Sohoku High School and a long-serving manager of the Sohoku High Bicycle Racing Club, having held that role since the first year of the storyline. Her family owns and operates the Kanzaki Cycle Shop, which has given her deep, practical exposure to bicycles and road racing from a very young age. Although she does not compete as a racer herself, she is extremely knowledgeable about bicycle mechanics and assembly, skills she developed by helping out at the family shop. Her brother, a former member of the bicycle club who now runs the shop, also contributed to her expertise.

As club manager, Miki is responsible for much of the behind-the-scenes work that keeps the team functioning, including organizing training, managing equipment, and offering mechanical support during races and practice. Her passion for the sport is evident in her dedication to the club and her genuine enthusiasm for cycling. She is a steady, reliable presence for the team members, providing encouragement and practical assistance when needed. Her key relationships are with the club's core riders, particularly the first-years like Onoda Sakamichi and Imaizumi Shunsuke, whom she supports throughout their growth as cyclists. She also interacts closely with the older club members and her brother, whose shop is a frequent resource for the team.

Over the course of the series, Miki remains a consistent and quietly indispensable figure, demonstrating growth in her organizational and leadership abilities as the club faces new challenges. Her notable abilities include a thorough understanding of bicycle mechanics, the ability to quickly diagnose and repair issues during races, and a solid grasp of race tactics and equipment choices, even though she never races herself. Her role is vital to the team's success, embodying the supportive backbone that allows the racers to perform at their best.