Kenichi is a pure-hearted young man living in an apartment in Tokyo. His wife's mother, Kaoru, comes to visit from her hometown for a three-day, two-night trip to see the city. A mature woman in her forties, Kaoru has a voluptuous and alluring figure. As she stays in Kenichi's home, her warmth and sensuality begin to deeply affect him, stirring emotions he's never felt before.