Miharu Shimizu is a female student at Fumizuki Academy, assigned to Class 2-D and serving as that class's ambassador. She first appears as a supporting character in the series and later takes on a minor antagonistic role. Her most defining trait is an intense, obsessive romantic fixation on her classmate Minami Shimada from Class 2-F, whom she addresses as Minami onee-sama. This devotion drives nearly all of her actions. She is relentless in following Minami around the school, often appearing unexpectedly, and she aggressively targets anyone she perceives as a threat to her relationship with Minami, particularly Akihisa Yoshii, whom she frequently attacks verbally and physically whenever he gets too close to Minami. Her hostility is not limited to Akihisa; in the light novel stories, she extends her fixation to other girls with flat chests, such as Aiko Kudou, indicating a broader attraction beyond Minami alone. Miharu's personality is characterized by a combination of passionate adoration, jealousy, and a willingness to resort to force or manipulation to keep Minami for herself. She has been described as a possible yandere due to this possessive and aggressive behavior. Despite her combative nature toward perceived rivals, she is content to remain in remedial classes if that means she can be with Minami. Her role in the story is primarily as a recurring obstacle to the romantic interactions between Akihisa and Minami, sometimes cooperating with other characters for her own ends. She does not undergo significant personal growth over the course of the series; her motivations and behavior remain consistently centered on her desire for Minami. Her notable abilities include her position as class ambassador, which gives her some authority in class-level activities, and her participation in the summoner battles that are part of the school's testing war system. Physically, she has short orange hair styled into ringlet pigtails and yellow eyes.