In this, Kang ShinWoo (Lee JungShin) is a math teacher with a good looking appearance. And Han JiSoo (Lee YeolEum) is his first love for the past 10 years but he has not forgotten. By an accident, he travels to the past when he was a high school student. There, he meets his younger self (Seo JiHoon). Kang ShinWoo struggles to make the younger Kang ShinWoos love come true.