It's a love story between the disobedient student Kang-wook and his teacher Yool-ju set in a high school in Chuncheon.
Before meeting Kang-wook, Yool-ju has been dating Tae-hyeon, a public prosecutor. But over time Yool-ju and Kang-wook fall deeply in love with each other despite social prejudices, the age gap and the teacher-student relation. One day, Yool-ju accidentally kills Kang-wook's classmate who intentionally harasses Kang-wook. But due to narcolepsy, Yool-ju doesn't remember what has happened, as she falls asleep during the incident. To protect her, Kang-wook goes to jail in place of Yool-ju.
Five years later, when Kang-wook is released from prison, he meets with Yool-ju again, but Yool-ju is engaged to Tae-hyeon. Learning what sacrifice he has made for her, Yool-ju wants to return to Kang-wook, but this time Kang-wook is not alone -- Ja-kyung, his former classmate and currently a radio program host, is beside him. The circumstances hamper Yool-ju from loving Kang-wook, but she is desperate to help him recover the lost five years and become a top-notch cook.