Koyori Kokubunji is a 17-year-old female model and student, characterized by blue eyes and dark blue hair. She works alongside Komugi Nakahara at the Kiri Pro talent agency, serving as both her friend and colleague. Koyori operates as a traditional idol within the industry. Her professional success exceeds Komugi's, partly due to her advantageous physical measurements. Despite this career rivalry, she maintains a friendly and sympathetic personality, achieving her status without envy or underhanded tactics. She specifically admires Komugi for wearing appealing costumes during their work.

Koyori possesses a dual identity triggered involuntarily. Periodically, she loses consciousness and transforms into "Magical Maid Koyori," becoming the antagonistic counterpart to Komugi's heroic persona. In this transformed state, her personality inverts completely, and she emerges as the primary antagonist, infecting innocent civilians with viruses. She harbors frustration over repeated defeats inflicted by Komugi and her sidekick Mugimaru. After these confrontations, she reverts to her original personality with no memory of her actions as Magical Maid.

In the sequel OVA *Magikarte Z*, Koyori's antagonistic role escalates significantly. Her transformed self successfully spreads viruses worldwide, achieving a temporary victory that results in Komugi's total defeat. This event marks the culmination of her antagonistic arc across the series.

Her Magical Maid Koyori character design includes animal ears, a headdress, stockings, and a tail, visually reinforcing her connection to the magical conflict.