Meet Tenjin, a 27-year-old teacher at a cram school preparing students for high school and middle school exams. Despite excelling with younger students, he harbors a disdain for children. Enduring his work routine, he mentors his coworker JD and navigates life's challenges. Everything changes when a fifth-grade student unexpectedly confesses her love, witnessed by 14-year-old Seika who then manipulates him into providing secret 'personal lessons' after hours.