Watashi wa Gitei no Omocha ni Narimashita

Follow the life of Ikumo, a woman who is married to Keisuke, and happy to be his wife. When her husband runs up some debts, he's able to borrow money from his younger brother Taisei who has had success in business. There's only one problem: Taisei wants Ikumo to provide some "pussy payments" because of the loan, and she's unable to resist whatever he asks.