Two orphaned sisters are left in a terrible position after their parents' deaths. They left behind only debts, which the girls are now responsible for. To pay the bills, they must become slaves for a dark organization. They begin their training under the guidance of a man who is determined to make them his masterpiece; the finest slaves he ever trained. If he succeeds, he will be able to retire from the organization, and absolve his own debt he has had to pay.