18-year-old Kang Kyung Joon's spirit suddenly becomes transplanted in the body of 30-year-old Seo Yoon Jae. Seo Yoon Jae is a successful doctor and engaged to high school teacher Gil Da Ran. Gil Da Ran just so happens to be the teacher of 18-year old Kang Kyung Joon.
The story is about two childhood friends, Joon-suh and Eun-suh, who grew up together but were forced to part ways when Eun-suh's family moved away. Many years later, they meet again by chance and rekindle their friendship.