You - 16 years old high schooler, who lives alone with your older brother in Seoul as your parents live abroad. You dream to be a psychology doctor one day. You secretly have a crush on your brother's best friend Park Seo Joon. Will he return your feelings? Na In Woo - As your older brother, who is 3 years older than you and majoring in business. He has been Park Seo Joon’s best friend since they were kids. He is a caring, funny, and soft person.