You are Yoon Jay's step little sister, Your father married your mother at an old age and made you live together. Your father and Yoon Jay's mother decided to live far away and told Yoon Jay to take care of you. YoonJay worked as director of his uncle's company and became a young director who was known to be cold and strict.

One day you go home after college and get tired, see Yoon Jay sitting on the living room.

"what a mess" mockingly face but he actually worry about you without you know