|Also known as||Zaki (by friends)|
|Occupation||Junior High School Student (High☆Speed！2)|
Elementary School Student (High☆Speed！1)
|Clubs||Iwatobi Junior High School Swim Club (High☆Speed！2)|
Iwatobi Swimming Club (former) (High☆Speed！1)
|Relatives||Shota Yazaki (older brother)|
|Light Novel||High☆Speed！1 - Ch. 2|
Aki Yazaki (矢崎 亜紀 Yazaki Aki) is one of the characters in the light novel, High☆Speed！, written by Kouji Ohji. She is a classmate with Haruka Nanase, Makoto Tachibana, and Rin Matsuoka at Iwatobi Elementary School. She is also in the Iwatobi Swimming Club, along with Haruka, Makoto, Rin and Nagisa Hazuki.
Aki's physical appearance is never mentioned in the light novel. However it is known that she usually wears a white muffler that is later stained brown when it accidentally falls into a river. In the manga, she's shown to have a short bob haircut with a small braid running down part of it on one side.
Aki is a kind, sweet girl who seems to have a "sunflower" smile. Because of her cheery disposition she always sees the silver lining in any situation. She is also someone who values the relationships she has such as wanting Haruka to depend on people and make friends, referring to her relay team as her sisters, and crying at her and the boys' elementary graduation ceremony. Even in stressful situations she can keep a clear head and take charge as seen when Haruka falls into the river while trying to retrieve her lost muffler. Her shouts alert Makoto and Rin to help her as she calls the ambulance, swim club, and Haruka's mother while Rin and Makoto rescue him.
In the same competition where the boys win first place in their relay, Aki and her friends win bronze in the girls relay.
Haruka Nanase - Aki highly regards Haruka. She and her lost scarf in the river beneath Misagozaki Bridge are major catalysts for his development. She puts in effort to understand his viewpoint, mentioning that she would have continued staring on glumly as her scarf floated away if he hadn't told her to leave it be. Because of Haruka being attentive to her, Rin thinks that out of everyone, it's more likely that she, along with Makoto, can get through to Haruka about joining the medley team. She, like Rin, also believes that Haruka would do well swimming in the medley as this might enable Haruka to see the benefit of relying on others.
Makoto Tachibana - Aki and Makoto have a good relationship, with the latter affectionately calling her 'Zaki-chan,' much like he would later call Rin's sister and the manager of the junior high swim club, Gou Matsuoka, 'Gou-chan.' Aki turns to him to understand Haruka better than she does and Makoto is supportive of her as a friend, as seen when she loses her scarf and when she forwards the idea of planting flowers around a lonesome cherry blossom tree as part of their elementary graduation project. Late in High☆Speed！ they share excitement over each other's medley team doing well, culminating in a high five between them.
Nagisa Hazuki - From the beginning, Nagisa calls Aki "Zaki-chan" affectionately, much like he later calls Gou "Gou-chan." Aki regards Nagisa as a little brother, but becomes taken aback by his large eyes, thinking that their gaze lays bare the swimmer she truly wants to be. She's shown to yearn "to swim with [her] honest feelings, like Nagisa does," and hates herself for being unable to answer him with certainty.
Rin Matsuoka - Unlike Makoto and Nagisa, Rin calls Aki "Yazaki-san." At one point she's led to believe, due to their joking around, that Rin is being bullied by the boys and promptly scolds them. She connects with him through how much they both want Haruka to join the medley, confirming during their conversation that she thinks of Rin as someone with a large personality. In her mind, she wonders how he's always "running towards somewhere," seeking something.
Shota Yazaki - Aki admires her older brother, as his being part of the swim club is the initial reason she also joins. However, she also displays annoyance and disappointment in her brother, as seen when her brother gets upset after losing a race to Haruka and getting banned from club activities. She calls him stupid and impatient for it, stating that he always orders people around and acts self-important.
- Despite what the anime shows, Aki is actually the one who comes up with the sentence, 'I swim best free for the team,' on the school bricks, according to the light novel.
- Although she plays an important part in the light novel and manga, Aki does not appear in the anime.