Mizukoshi Sayaka is a young high school teacher who appears as one of the main characters in G-taste. She is 24 years old, stands approximately 1.64 meters tall, and has long brown hair and brown eyes. She is often seen wearing glasses, earrings, and lipstick, and she dresses in a professional manner befitting her occupation. Her background establishes her as a dedicated educator, but her life takes a dramatic turn after she is sexually assaulted by one of her own students. This event triggers a profound change in her behavior: she becomes unable to control her arousal and finds herself constantly excited, even in completely inappropriate situations such as standing in front of her classroom. The experience leaves her struggling with an overwhelming obsession that she cannot manage on her own. In an effort to regain control, she confides her problem to Doctor Fubuki, a physician who offers to help cure her fixation, though his methods are ethically questionable. Later, Sayaka extends her own pattern of forbidden relationships by attempting to seduce Misuzu Kawamura, a student who looks up to her and is dealing with her own romantic troubles. Within the story, Sayaka serves as the representation of the teacher archetype among G-taste’s cast of stock erotic figures. Her narrative focuses on the internal conflict between her desire to maintain a prim and proper professional image and the compulsive sexuality that now defines her actions. She appears in the OVA episode dedicated to her character and also features in the original manga and live-action drama adaptation. No special abilities or skills beyond her teaching role are depicted; her defining trait is the psychological and behavioral transformation triggered by the assault. Her development is limited to this shift from restrained professional to someone who willingly pursues inappropriate entanglements, first with a medical professional and then with another student.