A friend who died young, Natsumi has been working as a housekeeper at the Kimura household for the past year. She had built a good relationship with the master and his eldest son, Daisuke, but the second son, Yuusuke, was reluctant to open up to her, causing Natsumi to worry alone. One day, the master was scheduled to go on a one-month overseas business trip, and Natsumi decided to live in at the Kimura household for work... On the first day, Natsumi took a bath to relax. However, when she got out of the bath, all her ＜panties＞ were gone…
