Maki Koizumi has recently been suffering from severe sexual frustration due to the near absence of intimacy with her husband. As a result, her attention turns to her father-in-law, whom she begins to desire. She starts provoking him in daily life, deliberately exposing her cleavage when helping him change clothes or thrusting out her hips to reveal her underwear. Her father-in-law notices her behavior, and gradually finds himself becoming aroused by her. No longer merely in-law, they evolve into lovers who crave each other.