The wife is returning home to her hometown in preparation for the birth of her child. Her sister, Miho, comes to visit because she thinks it would be inconvenient for the man to be alone. The man gratefully accepts his sister-in-law's kindness, but... Miho's true target is a penis. Miho, whose marriage has not been going well and she has fallen into a sexless marriage, has set her sights on her brother-in-law as a way to relieve her sexual frustration. The temptations that Miho unleashes one after another are so erotic and sensual that they easily shake the man's feelings that he cannot betray his wife...