Naive young man Kenichi has been captivated by his wife's mother, Maya, who's been staying at their home since last weekend. Her mature, voluptuous body leaves him flustered and breathless. One morning, he's drawn to the sight of his mother-in-law cleaning the floor, her plump, shapely buttocks swaying with each movement, making him stare in fascination. His wife notices and urges him to eat breakfast quickly. With Maya's stay set for three nights and four days, Kenichi's heart races nonstop. Before long, his lower body spirals out of control, growing increasingly aroused beyond restraint.