She Is Nineteen (2004)

The story revolves around Yoo-min, a 19-year-old girl who was abandoned after the death of her mother. She lives alone in with her adoptive brother, Kang-pyo. One day, she meets Min-jae, a doctor who treats her brother, and instantly falls in love. So she readily agrees when Min-jae asks her to pretend to be his fiancee, so that his nagging mother will stop pushing him to marry a tycoon's daughter. Yoo-min and Kang-pyo move into Min-jae's house. But his younger brother, 19-year-old Seung-jae, goes to the same high school as Yoo-min and secretly has a crush on her.