Maiko Fujishima is a student in class 1-C at Yamaboshi High School, where she initially serves as the class representative before later joining the student council. She is the daughter of a high-ranking police officer, a background that contributes to her natural air of authority and responsibility. On the surface, Fujishima is the embodiment of a model student, appearing intelligent, mature, beautiful, and well-respected by both her peers and teachers. She is highly perceptive, often noticing details that others overlook, which leads her to become aware of the strange behaviors exhibited by the members of the Student Cultural Research Club.

Beneath this flawless exterior, however, Fujishima possesses a considerably more eccentric and deviant personality, which she tends to reveal only when alone with the club members. One of her most defining traits is her intense, open, and often lustful crush on her classmate Iori Nagase, which she makes little effort to hide, much to Iori's horror. This infatuation fuels her quirky sense of humor and her sadistic delight in watching Taichi Yaegashi fumble in his own romantic pursuits with Iori, whom she considers her rival. Despite this antagonistic view of Taichi, she fancies herself a "Missionary of Love" or love expert, and she is often willing to offer him sincere and wise counsel when he faces difficulties in his relationships. Her sense of responsibility is strong, and she is genuinely happy to provide help to her fellow students, showing a capacity to set aside her personal desires for the greater good. For instance, she loans her bicycle to Taichi to help him find a distressed Iori, recognizing that her crush needs her rival more at that moment.

Throughout the story, Fujishima acts as an observant and sometimes interfering figure to the main group. Her role is often that of an outside catalyst, providing support, comic relief, or a different perspective on the supernatural phenomena and interpersonal conflicts they face. She is one of the few characters outside the core group to deduce the supernatural nature of their troubles. Her key relationships are varied. With Iori Nagase, she is an ardent pursuer who also genuinely cares for her well-being. With Taichi Yaegashi, she shares a complex dynamic of rivalry and mutual respect; she both torments and advises him. She has been shown to conspire with Himeko Inaba, the two of them using their wits to scheme for their own devious ends. Shingo Watase holds a crush on Fujishima, though she appears largely oblivious to his affections.

Fujishima does not undergo a dramatic personal transformation, but her character does show development. She evolves from strictly obeying authority figures, such as the student council president, to thinking and acting for herself. Her confidence in her own judgment grows as she learns to prioritize her own beliefs over simple obedience. While she has no supernatural abilities, Fujishima possesses notable ordinary skills. Her most prominent ability is her keen perception, which allows her to see through the club members' attempts to hide their supernatural experiences. She also considers herself an expert on romantic matters, a role she takes seriously. Her family connections as the daughter of a senior police officer also give her access to information and influence that other students lack.