Kanzaki Miki is a first-year student at Sohoku High School who is the younger sister of Kanzaki Tooji. Given that her family owns and manages a bicycle shop, she has been exposed to the world of bicycles and road races since she was very young. While not a road racer herself, she is very passionate about anything that has to do with the sport. When not at school or doing club activities, she helps out at the shop as another mechanic.
She is currently the manager of the Sohoku High Bicycle Club.
Kanzaki Miki, like her older brother, has brown hair and brown eyes. She has a slender frame and is of average height. Her straight hair reaches down to her waist and she has bangs. It is noted occasionally that she sports a larger than average bust size. She usually does not sport any hair accessories, but after the summer break training camp, she is seen wearing a white clip with a purple fish decoration parting her bangs. She often wears Sohoku High's uniform which consists of a white blouse concealed within a buttoned up green jacket, a white and red striped ribbon tied around her collar, red and yellow plaid skirt, and black socks paired with brown school loafers.
During the Inter High competition in Hakone, Miki wore a pink polo shirt and a white skater skirt along with a light blue visor at times.
Miki is shown to be very supportive and kind, as illustrated when she reaches out to advise Onoda during their first meeting and during his subsequent races. She is very passionate about bicycles, often sharing some of her extensive knowledge on the subject with Onoda or her friend Aya. Aya observes that she "usually has her head in the clouds" unless the conversation turns to bicycles, upon which she becomes notably more energetic and talkative. She has a tendency to "sparkle" when she becomes excited, similar to how Onoda acts when he becomes engrossed in talking about anime. She is described multiple times as a "bike otaku" and doesn't seem to think her passion is strange.
Miki has a mischievous streak that comes out several times, such as when she slyly reminds Makishima that he had claimed it was impossible for Onoda to beat Imaizumi to the peak during the First Year race. She is sometimes seen gently teasing Imaizumi or Aya.
Like her brother, Miki is shown to be highly observant. While this mostly applies to bikes and cycling, she occasionally notices the different states of the members of the cycling club, such as when Kinjou withdraws from the others during the ride home from the Inter High, or when she is the first person to notice Imaizumi favoring one leg during second year.
Miki can be very serious and stern, defending her team when others insult it, yet keeping a clear head and rarely becoming unreasonable when angered or under pressure. She cares for the well-being of Onoda and the rest of the team, and often takes on a more solemn and focused air during races, particularly when Sohoku is in a pinch.