Due to her weak constitution, the youngest daughter of the Rotary family does not come out of the house. A vulnerable lady, Crystal Rotary. In fact, she is a man. A family where only girls are kept alive and boys are either become corposes or heirs. With no influence nor strength, Crystal's only goal is to leave the Rotary family and live a normal life. Growing up like a daughter to survive and holding his breath like a dead man. After finally escaping, he's getting married? Backed into a corner, Crystal proposes to Grand Duke Pentrine, who is politically at odds with the Rotary clan. Thinking that his proposal was going to be rejected, a letter of marriage approval returns, and Crystal escapes to Pentrine's estate. The cold master of the North, a cruel person with an ice-cold heart. Crystal meets Ilian Pentrine and got married. How did that happen?