Arina Hashimoto, a dedicated female teacher at a school, had been in a romantic relationship with a senior colleague, but recently his presence has faded, leaving her feeling increasingly lonely. Her struggles extend to her teaching, as she finds it difficult to connect with her students, causing her stress to build. One day, a vibrator confiscated from a student leads to the discovery of her secret masturbation habits. Initially resisting fiercely, she is gradually treated like a plaything, and her emotional defenses begin to crumble.