Worried about her close friend's son Yuta struggling with his grades and lack of motivation as a student, Eri decides to take action out of concern for his future. When she visits his room, she catches him masturbating. Believing that satisfying his sexual desires might improve his focus, she promises him, "If you work hard, I'll have sex with you." This promise sparks a dramatic shift in his attitude, leading to an intense and provocative development.