On her wedding anniversary, Yui planned a hot spring trip with her husband Ryuichi and her father-in-law. However, Ryuichi was delayed due to sudden work, leaving Yui to begin the journey alone with her father-in-law. Initially feeling awkward, Yui gradually grows more comfortable in his presence as they tour the onsen town and draw emotionally closer. When her father-in-law asks her to wash his back in the bath, she shyly agrees, opening her heart to his gentle touch. Later, when Ryuichi finally arrives, he acts cold toward her, deepening Yui's sense of loneliness. Sensing her sadness, her father-in-law responds with increasing warmth and affection. As their bond strengthens, Yui eventually bares her beautiful body to him in the bathing area.