Weekend. In an apartment in Tokyo, hardworking salaryman Shintaro is tidying up the room in a rush to welcome his wife's mother, who will arrive shortly. His wife's mother, who lives in the countryside, has taken a long train journey to the city to check on her daughter and son-in-law. The doorbell rings "ding-dong," and soon stepmother Chisato Shoda walks in. Struck by her voluptuous figure, Shintaro catches his breath, completely captivated for a moment.