Sayoko Saeki maintains an undercover identity as a school nurse and counselor to facilitate a drug investigation. She possesses aubergine hair, blue eyes, and a notably attractive figure characterized by a nice face, slender body with perfect curves, and a well-formed bust. Professionally, she cultivates a friendly, understanding, and kind demeanor, expertly building trust. This carefully constructed persona masks her true nature as a vampire-like entity reliant on feeding upon male life energy through sexual encounters. Several students recognize her from recent prior sexual interactions, exposing her covert activities. Her feeding necessitates engagements with multiple partners simultaneously, and prolonged engagements inevitably prove fatal. She typically selects criminals as her victims. However, states of intense arousal can trigger a loss of control, causing her to target partners indiscriminately, beyond her usual criminal focus. Her mission objectives and predatory existence coexist without direct conflict, as her actions serve both her physiological needs and her undercover role.