Returning home late at night, "Satomi" hears strange noises coming from a classroom and discovers "Riko" calling out her own name while masturbating in the empty room. Riko, a new female teacher, and Satomi, her supervising instructor—both supposed to uphold professional integrity—begin an impure lesbian relationship from this moment on. The story unfolds their evolving connection, portraying the intense intimacy and raw desires binding them together.