Pay off your brother's debt by having sex with the creditor

Natsume is a married woman whose married life was happy when something bad happened. Natsume's older brother owes a large amount of money to the gangsters and his life is in danger. As a younger sister, she cannot leave him alone. Natsume hid from her husband to go meet that gangster to negotiate for her brother. She brought some money but it was not worth much compared to the large debt, so her body would be used to pay off her brother's debt. Every evening she had to go to the boss and make love to him for half a year.