Kimijima Mio lives happily with her husband and her father-in-law, who is 80 years old and not in good health, so she is always by his side to take care of him. Her father-in-law is a very good person, and taking care of him brings Mio happiness.
Not only that, but there is also a secret between them that Mio cannot tell her husband: she takes care of her father-in-law from A to Z, even fulfilling his 'needs.'
But she never crosses the line; she only helps him with her hands and mouth, and during one market trip, her father-in-law fell because he needed to go to the bathroom.
Her husband saw this and wanted to take him to a nursing home for his safety. He quickly arranged a place for him without consulting Mio and her father-in-law first.
There are only four days left for her father-in-law to stay here. Mio realized that she wanted to be with her father-in-law more than ever, she wanted to have more memories with him and then they both crossed that last line.
The two frantically made love to each other over and over again, making a lot of good memories together in the little time left...
