Rea Katagiri is a disciplined secretary tasked with supporting Reito Mizuhara, a pivotal leader combating a global virus targeting men. Though integral to managing his daily operations and aiding vaccine research, her collaboration begins with hostility rooted in a mistaken belief that he assaulted a colleague—an incident later proven accidental. Her lingering distrust fuels a cold professionalism, masking a visceral disdain for men.

With long black hair, striking purple eyes, and a polished demeanor, Rea blends professional attire with subtle elegance. Her rigid demeanor conceals an obsessive streak, most evident in her infatuation with colleague Mira Suou. She openly admires Mira’s beauty, seeks physical closeness, and attempts to isolate her from others, particularly Reito, whom she views as a threat.

Rea’s loyalty centers on her younger sister, Mimi Mannen, who aids refugee-district operations. Protective to a fault, Rea employs a taser to shield Mimi from harassment and collaborates with her on covert missions, including orchestrating Reito’s escape from Japan via a prearranged vessel. Despite personal contempt, she pragmatically supports Reito’s crisis efforts, assisting in vaccine distribution and subtly ensuring his safety during terrorist attacks.

Her growth emerges through reluctant interactions with Reito’s team, where she begrudgingly acknowledges his altruism. She strategizes to ease political tensions within their organization, balancing public relations with crisis management. Unresolved romantic tension with Mira and rivalry with Akane Ryuzoji underscore her emotional complexity, while covert investigations into the virus’s origins and counter-terrorism missions against groups like Izanami mark her shift from bias-driven antagonist to a calculated, if conflicted, ally in humanity’s survival.