After a tragic car accident, 18-year-old Kang Gyung Joon discovers that his spirit has been transported to the body of 30-year-old Seo Yoon Jae. Yoon Jae is a successful doctor who is engaged to high school teacher Gil Da Ran. But Da Ran just so happens to be Gyung Joon’s teacher. What is a boy to do when he discovers that he has become his own teacher’s fiancé by a freak of nature? Will he be able to return to his own normal life or is he doomed to live out the older man’s instead?