Mary Wi wants to be an eco-friendly designer. One day, Mary goes to a glam rock concert and sees rocker, Mu-gyul. Mary's dad has already arranged Mary's marriage with Jung-in. To avoid the arranged marriage, Mary asks Mu-gyul to take a wedding photo. Now, Mary will live in a pent house with Jung-in while she lives with Mu-gyul, at the same time. After 100 days, she has to choose Mr. Right.