Soda lives in a miserable life after her parents died in a car accident 5 years ago. She has a 12 years old sister who lives with her aunt. To be able to live together, Soda promised her sister to have a stable job.
She was hired to be a housemaid in a mansion which was built in the middle of a lake and located 80 km from the city. The first day of her staying, she realized that the owner of this house doesn't need a housemaid but they need a virgin girl to marry to a mysterious ancient sword.