Located in the deepest part of Cheorwon, Gangwon-do, where the mountains are clear and the water is pristine, lies the Etiquette School. There, a young teacher named 'Songyi' (Jin Ji-hee) boasts extraordinary knowledge and charisma despite her young age. The biggest crisis in 'Songyi's' 13-year life has arrived: straightening out 'Duyeol' (Ahn Nae-sang), a problematic adult abandoned by society. 12 years of waiting... but the time for farewell passes too quickly! In fact, 'Songyi' is the daughter 'Duyeol' lost 12 years ago! Keeping this secret, 'Songyi' doesn't give up and shows her sincerity, even as she clashes with 'Duyeol' at every turn. 'Duyeol' later realizes that 'Songyi' is his daughter, but the time left for them is far too short...