Miyama Mizuha presides over Kitanohashi High School’s manga research club, fiercely opposing the magic club as its rival. With a domineering demeanor, she commands steadfast loyalty from her members, wielding her imposing stature and striking physique—notably her prominent bust—to fluster childhood acquaintance Takeo Takakura. Their relationship, forged through years of relentless teasing and pranks, persists into high school, marked by Mizuha’s sharp provocations.

Beneath her abrasive exterior lies unspoken affection for Takeo, masked by barbs and antagonism. Her hostility thinly veils a desire to monopolize his attention, fueling a rivalry steeped in unresolved tension. This competitiveness drives her relentless campaigns to sabotage the magic club’s foothold, often targeting their shared clubroom to reassert control.

During the Bell’s metamorphosis into a colossal cherry blossom tree, Mizuha momentarily intervenes in the TV series, steering a blimp to parley with the entity. Though swiftly overruled by military forces, her audacious defiance in confronting supernatural forces without innate magic highlights her boldness. Her character remains steadfast in balancing sharp assertiveness with veiled fragility, maintaining unchanged relational and conflict-driven behaviors throughout documented appearances.