A 19-year-old girl falls in love with a hospital houseman. He asks her to pretend to be his fiancee, so that his nagging mother will not push him to marry a tycoon"s daughter. But he doesn"t know that his younger brother, a 19-year-old high school student, is having a crush on her... What will happen to this teenage boy and his so-called future sister-in-law?Unlike other tear-jerking K-dramas, My 19 Year Old Sister-in-law is a light romantic comedy that will touch you and make you laugh at the same time. Four popular Korean TV stars Kim Jae Won, Yin Ji Shang, Jung Da Bin, and Jin Min Shan join hands in entertaining you with a 20-episode drama series.