Mizuki Himeji, a second-year Fumizuki Academy student, attends Class F after a fever-induced absence during her entrance exam left her with a zero score—despite ranking as the school’s second-highest academic achiever. Her delicate frame stands at 150 cm, accentuated by a buxom figure, light pink hair secured by a rabbit-shaped clip from childhood friend Akihisa Yoshii, and observant purple eyes. Though polite and soft-spoken, her serene demeanor conceals yandere impulses, particularly when others encroach on Akihisa, her unacknowledged romantic obsession since elementary school.

Her romantic awakening crystallized during summoning exams, yet confessed affections repeatedly unravel through mishaps, such as rival Minami Shimada’s claim to Akihisa’s first kiss. Despite academic prowess, she doubts her allure, misinterpreting Akihisa’s attention as mere kindness while remaining oblivious to admirers.

Notorious for culinary disasters, Mizuki crafts meals blending ingredients by symbolic logic rather than flavor, producing corrosive concoctions feared for their venomous aura and potency. Her summoning avatar manifests as a sword-wielding knight in Western armor, unleashing searing heat rays, though system glitches morph it into a succubus-like entity mirroring her boldness and physique.

Prone to dust allergies and physical frailty, she counters fragility with tenacity in pursuing Akihisa. Secret hobbies include stitching dolls and curating clandestine photos of him cross-dressing. Alcohol strips her restraint, unleashing audacious advances.

Class F’s chaos and Minami’s rivalry fuel her growing assertiveness, while Akihisa’s steadfast support slowly chips at her naivety. Yet her essence—earnest devotion and guileless loyalty—endures unwavering.