Nam Se-Hee (Lee Min-Ki) is a single man in his early 30's. He has chosen to not marry. He owns his home, but he owes a lot on his mortgage. Yoon Ji-Ho (Jung So-Min) is a single woman in her early 30's. She does not own a home and envies those that do. She has given up on dating due to her financial struggles.
Yoon Ji-Ho begins to live at Nam Se-Hee’s house. They become housemates.
It tells the love story of two childhood sweethearts that spans 19 years. Chen Xiao Xi is a cute and small girl with a lot of positive energy. She gets to know Jiang Chen, a tall and proud genius boy, at school and tries everything to pursue him. The drama depicts the beautiful and pure heart throbbing love of seventeen years olds, but also delves into the topic of making mistakes andhow to find back to each other again.