Ai Finance, which operates in the suburbs of Tokyo, is known to some as a loan shark with high interest rates. When lending money, they have the debtor assume that he will be unable to repay for some reason, and when they lend money, they make a woman, either a family member or a close relative, act as a guarantor. If the debtor defaults on the payment, they will kidnap the woman and sell her off to collect the debt. Rei, a teenage girl who is forced to pay off her gambling-addicted father who got into debt with this notorious loan shark, falls into the fate of being forced to work in place of her hospitalized father to repay the debt...