To insure the inheritance of their family business, parents of four girls decide to raise their youngest daughter as a boy.

Jang Ha Na is the fourth daughter of the eldest son of a family that's been making soy sauce for hundred of years. She has to dress up like a man because of their financial situation. The family needs a male representative for their soy sauce business. After giving birth to four daughters, they gave up for trying for the male heir and the fourth daughter will just have to pretend to be a boy and act like a son within the family.