Miki is the younger sister of Tooji, a former captain of Sohoku's bicycle club and the current manager of their family's bicycle shop. Though not much of their relationship is shown, they seem to get along very well.
Miki is a childhood friend of Imaizumi's. When they first met, she instantly tried bonding with him over their interest in bikes, only to be rebuffed by him. Miki has a tendency to lightly tease Imaizumi or push him into doing what she wants. Though Imaizumi is sometimes frustrated by Miki's actions, such as when she invites spectators to his first race against Onoda, they have maintained a friendship throughout the years. Presently, Miki is pleased about the positive changes she has seen in Imaizumi's personality since he has joined the bicycle club.
Aya, a member of the tennis club at Sohoku High, is Miki's best friend. Aya is the one who initially describes Miki as a "bike otaku" and tends to criticize her for "having her head in the clouds" or getting distracted from important or obvious things due to her love of cycling. She has very little interest in cycling and is often put off by Miki's sudden bursts of passion over the sport. Miki also tends to lightly tease Aya for being prickly or awkward when trying to be nice to Onoda, much to Aya's displeasure.
Despite all of this, the two get along quite well. Aya cares a lot for Miki to the point of being somewhat overprotective of her, as seen when she hits Onoda for acting (in her eyes) untoward towards her and when she calls Miki "helplessly cute" for not suspecting Onoda of lying to her to impress her.
In second year, Aya tags along with Miki and the rest of the support crew to the Interhigh when her own team loses their qualifiers, often turning to Miki when she becomes confused about the state of the competition. Though she often vocalizes her displeasure about all the work they have to do, she seems to be becoming more and more interested in cycling.
Miki calls her "Aya-chan."
Miki has been very friendly towards Onoda starting from their first meeting, which makes Onoda think that even people from sports clubs can be nice. She even does research to find out about him because she was curious about his cycling. She often talks to him during school, which Onoda is both embarrassed about and appreciative of. Miki is the one who corrects Onoda's saddle position during his first race with Imaizumi, as well as supplies him with a road racer later on. She constantly cheers Onoda on during races and is amazed at his rapid progression as a cyclist. While Onoda continues to be easily flustered around her, the two can certainly be considered friends. Onoda calls her "Kanzaki-san."
Although Miki is generally regarded as behaving kind and motherly to her team members, she hit Naruko once after he pointed out that her breasts "grew" after summer break. Since this is the only act of violence Miki has displayed, it seems that she did not appreciate Naruko's remark, although, in actuality, he honestly believed he was giving her a compliment. For the most part, however, the two are typically on good terms. Naruko calls her "Manager."
Like others, Miki is often seen visibly bemused by Sugimoto's loud bravado. Sugimoto notes that she pointedly ignores him while congratulating the other first years for doing well at training camp. Despite this, Miki actually seems to admire Sugimoto for working hard and never giving up, as she compliments those aspects of him a few times (though never to his face).