Mizuki Kurahashi is a student at the same high school that Misa Kuroi transfers to in the story. She is one of the first students to approach Misa and quickly becomes her friend. Mizuki is talkative and willing to share information about the school, including details about a secret lesbian relationship between a student, Kazumi Tanaka, and a teacher, Kyoko Shirai, as well as the story of a locked classroom where a teacher committed suicide. On the surface, she appears to be a helpful and ordinary classmate, but as the plot unfolds and students begin to die under mysterious circumstances, her true role is revealed. Mizuki is the one responsible for the supernatural attacks and murders that plague the school. She admits to being the mastermind behind the killings, explaining that she seeks to summon Lucifer in order to dominate the world. Her motivations are driven by a desire for power and control. She uses dark magic and rituals, including the formation of a giant pentagram and the use of voodoo-like methods, to achieve her goals. Her relationship with Misa evolves from apparent friendship to direct confrontation, as Misa, a witch herself, stands in opposition to her plan. Mizuki ultimately reveals a sinister and ambitious personality that contrasts sharply with her initial friendly demeanor, but she shows no notable character development beyond this revelation; she remains steadfast in her malicious intentions. Her abilities appear to be rooted in black magic, allowing her to orchestrate the deaths of her classmates and to perform the ritual necessary to summon a demonic entity.