Chisato Mineta (Maki Horikita), a 20-year-old homeless girl who moves about from parks to net cafes.

Her mother died of illness, and when her father disappears after earning an incredible 100 million Yen debt, she is chased out of her home.

Where then a president of a huge toy company (Okura Shinzo) comes and rescues her by paying off the debt but then tricks her into marrying him.

If she stays married to him then she does not have to pay back the debt but if she leaves then all the money has to be returned immediately in cash.

She must also live in the Trick Heart Castle with his six sons, all adopted to be successors of the company, and act as their mother for three months in order for the debt to be fully paid.