Mayu has a strikingly similar appearance to Risa's friend, Chiharu Tanaka. In the anime, Mayu is a carbon-copy of Chiharu save for her hair color which is seen as a gray color. She retains the same petite body and blue eyes as Chiharu as well. In the manga, Mayu is never seen in color, but it is noted by Risa that Mayu is a "Chiharu with her hair not inked in." Mayu is first seen in her school uniform consisting of a light gray blazer with a matching skirt, a blue ribbon and knee-high socks, a light blue vest, and brown dress shoes. Mayu is only see a few times when not in her uniform, usually wearing a long coat and scarf.
- "Giant Baba": "Giant Baba" is the nickname given to Mayu's boyfriend by Ōtani and Nakao due to his height (3m tall), his real name is never mentioned. Mayu fell for him while dating Ōtani and ultimately broke up with Ōtani for him. The pair briefly broke up during Christmas break of their first year of high school for unknown reason, but got back together shortly after.
- Atsushi Ōtani (previous): Ōtani and Mayu dated during junior high. Mayu broke up with Ōtani shortly before their junior high graduation leaving him crushed. Ōtani claims that Mayu broke up with him because he was short, but in realty, she broke up with him because he neglected their relationship to focus on basketball. Although it isn't made clear, it appears that Mayu may have been cheating on Ōtani with Giant Baba. After Giant Baba broke up with her, Mayu had the intention to ask Ōtani out again, but never got the chance before her and Baba got back together.
- Brother: Mayu's older brother was the captain of the middle school basketball team that Ōtani and Nakao were on. He is extremely protective of his younger sister to the point that it scared much of the team to even be near her.