Naive young man Daisuke finds his heart racing at the alluring charm of his mother-in-law, Rumiko, who has been staying at his home since last weekend, leaving him in constant excitement. Each morning, he can't help but be captivated by the sight of her plump, shapely buttocks rising as she bends over to clean the floor. His wife notices and urges him, "Hurry up and eat your breakfast." Though Rumiko's stay was supposed to last only three nights and four days, Daisuke's emotions and body grow increasingly heated with each passing moment they spend together, until finally his lower body reacts beyond control.