Maria Imai, a dark-haired, bespectacled founding member of the East Oizumi Academy cosplay club and former miko, fiercely protects her younger sister Athena. Though too young for the academy, Athena participates in club activities, drawing unwanted attention from foreign exchange student Jenny Matel. Maria is prone to fainting spells when Jenny interacts with Athena due to Jenny's inappropriate attraction. Shy in private moments, Maria wears a purple towel wrapped around her head while bathing alone in an onsen during a training camp trip, standing up abruptly at the sound of a mysterious man's chuckle.

Her protective instincts drive her to physically shield Athena from Jenny's advances and issue direct warnings. When Jenny teases her about having a sister complex, Maria's vehement denial causes Athena to misinterpret it as rejection, leading to heartbreak; Maria later attempts to clarify. During the club's beach training camp, Maria participates in speed sewing and speed-changing challenges, struggling with the latter, and listens to local folklore about the River Ceremony festival alongside other members. Her club role centers on supporting activities while vigilantly safeguarding her sister's wellbeing.