Aki Mizutani is one of the three central female characters in her friend group. She is a high school student with brown hair that falls to her neck and black eyes, giving her a typical and approachable appearance for a teenager. Her personality is best described as fun-loving and boy-crazy, especially at the start of the series, where she embodies the role of a full-fledged romantic and a girly girl. She is a close friend of Chiharu Nitta, and the two often support each other through the ups and downs of their romantic lives.

Aki’s primary motivation throughout the story is her pursuit of a genuine romantic relationship. At the beginning of the series, she still harbors feelings for Tsuyoshi Ueno, a boy she had a crush on during middle school. Unfortunately for her, Ueno is an aspiring photographer who is so focused on his art that he is oblivious to her romantic interest, leading to considerable frustration for Aki. Her role in the story is to represent the longing and impatience of unrequited love, as well as the challenges of maintaining a connection. Unlike some of her friends who are involved in sports or other hobbies, Aki’s storyline is heavily centered on her emotional life and her desire for a boyfriend.

In terms of key relationships, her connection with Tsuyoshi Ueno is the most significant, particularly in the fourth episode, "Bitter Sweet Rain," which focuses on her attempts to get him to notice her as more than just a friend. She is also a loyal and caring companion to Chiharu Nitta, as they often confide in each other. Her friendship with the other main girl, Yumi Kazama, helps round out the trio, as their different personalities and tastes complement each other. As the series progresses, Aki undergoes notable development. While she starts off as a boy-crazy girl pining for an unavailable love, her situation eventually changes. She enters a relationship with her photographer boyfriend, who later moves to Hokkaido for work. This forces Aki to adapt to maintaining a long-distance relationship, which becomes a central aspect of her life for most of the series. She does not possess any notable physical or supernatural abilities, as the series focuses on realistic, everyday high school experiences and emotional growth. Her strengths lie in her persistence and her capacity to care deeply for others, even when the circumstances of love are difficult.