Ichiya's wife is pregnant and staying at her parents' home, leaving him to struggle with housework for the first time. No matter how hard he tries, the house remains a mess, and his days are filled with stress and exhaustion. Just then, his wife's older sister, Yuri, suddenly shows up at his door and offers to help with the chores. Surprised but grateful, Ichiya warmly welcomes her. Unbeknownst to him, Yuri's true intention is to relieve her long-suppressed stress and sexual frustration. Oblivious to her motives, Ichiya happily accepts her help and begins to relax in the bath. As he soaks, Yuri slyly smiles, washes his back, then quietly slides in beside him...