When Seiji Sanada, a 30-year-old salaryman, unexpectedly time-travels back to his high school days, he seizes the opportunity to finally confess his love to his adored history teacher, Haruka Hiiragi. Much to his surprise, she responds with a resounding 'Yes'! As they embark on a discreet relationship, Seiji quickly realizes that Hiiragi-sensei's affections know no bounds. Their journey into a flirtatious and indulgent rose-tinted school life commences with unexpected twists and turns.