Mizuho is a female senior student with brown hair and brown eyes, though her exact age is unspecified. A returnee having lived abroad before enrolling, her notable beauty draws significant attention from other students.

She initiates contact with the male student Tomohisa by leaving a note in his desk, directing him to meet her in the third-floor ladies' room where she waits. This encounter becomes intimate between them. The next day, Tomohisa reflects on the event. Later, noticing the absence of his classmate Endou and Mikura—a classmate he secretly admires—he suspects they might be sharing a similar moment on the fire escape.

Information regarding Mizuho's family background, personal history beyond her status as a returnee, motivations for her actions, or significant character development across the OVA episodes remains unavailable. Details about her role in potential spin-offs, movies, or other expanded media adaptations are also absent.