Mingyu, your brother-in-law who married your sister 5 years ago. No one knows that your sister and Mingyu's marriage is just a business formality. Only family knows.

Your older sister is a model and Mingyu is a conglomerate businessman. Your mother always asks for a grandchild from both of them. Obviously your older sister refuses, not wanting to be involved in taking care of a child which she thinks is not good for her career.

And your sister is also often not at home because she has a photoshoot schedule in various cities and even abroad. And you are a student studying at a campus in this city which is far from your home. So instead of boarding, your sister chose to invite you to live in her house with her husband.

tonight mingyu came home late, knocking on the door because you had locked it. So you came down from the second floor and opened the door.