Yome no Imouto to H na Kankei ni Natte Yabai!?

Yuusuke and Miori live their marriage happily, however one day they have a fight due to a trivial matter. Suddenly, the plans that to spend their vacations go to waste. To kill time, one of his friends recomend him a suspicious store. There he meets Hiori, his wife's younger sister. She doesn't want to be known that she works there, so she proposes a naughty deal with Yuusuke...