One day, the tax office receives a phone call. It was an accusation call that the inn where Nanao works as the landlady is evading a considerable amount of tax. Immediately, tax officials Oiwa and Inoue went undercover to the hot spring inn where Nanao was. Nanao, who noticed a staff member staying at a hot spring and conducting an undercover investigation, planned to somehow escape the tax audit by giving the staff a very dangerous erotic trick in a lewd yukata.