Seowoo and Jihyeok were once casual sexual partners. After they broke up, Seowoo pursued his dream of becoming a teacher, cutting off all relationships with men. He finally achieved his goal, but then Jihyeok reappears as a fellow teacher at the same school, constantly getting under his skin. Tormented by the memory of their past, Seowoo orders an adult toy, only to be caught red-handed by Jihyeok. Jihyeok uses this as leverage, issuing a subtle threat, and this incident forces the two to become dangerously entangled once more. A desperate teacher trying to move on meets the past he tried to bury. Will this dangerous reunion ruin Seowoo's new life, or does Jihyeok have a different, more twisted motive for their mandatory "back to" relationship?