While his wife is away on a trip, his mother-in-law arrives from Aichi. She came to help with housework, but now he has to live under the same roof as his big-breasted stepmother, and the situation becomes unbearable. Drawn to her deep cleavage, he is overwhelmed by uncontrollable desire. Ordinary daily scenes suddenly turn into tempting moments. His heart races as he wonders how his relationship with his stepmother will develop.