Natsumi has been working as a housekeeper at the Kimura family home for the past year, since her friend, who passed away at a young age. She had a good relationship with her husband and the eldest son, Daisuke, but the second son, Yusuke, has a Kokoro time opening up to Natsumi, and Natsumi is worried about this. One day, her husband goes on a business trip overseas for a month, and Natsumi ends up working and living at the Kimura family home... On her first day, Natsumi takes a bath to relieve her fatigue. However, when she gets out of the bath, all of Natsumi's panties are gone...