Riku, Ichika's homeroom teacher, is introduced by Ichika's mother as her new boyfriend. In reality, Ichika already has a boyfriend, but she has secretly been in love with Riku and has always been drawn to him. When Riku gets drunk at her home, Ichika impulsively kisses him. Though Riku knows it's wrong to get involved with a student and the daughter of his girlfriend, he can't suppress his growing feelings for her. Soon, Ichika takes control, determined to make Riku hers. Through intense domination—including reverse anal torture—she pushes him to confront his true desires. She seeks to possess his heart completely, making him believe that only she can truly satisfy him. As their forbidden bond deepens, their relationship evolves into something darker and more intimate.