While his wife was pregnant and visiting her hometown, Tatsuya was enjoying living alone for the first time in a long time. However, after only a week of living alone, he started to feel lonely and yearned for company... Then his sister-in-law Tsubasa came to help with the housework. Tatsuya was happy to welcome her unexpected visit. However, Tsubasa's real purpose was to relieve her sexual frustration with Tatsuya while his wife was away visiting her hometown. Tatsuya, unaware of her plan, was soaking in the bathtub... when Tsubasa came in...