Chisato Shoda, the mother of Haruki, is a single mother who divorced 15 years ago. She has always seriously considered her son's future, working hard and dedicating herself completely to ensure he graduated from university and grew into a respectable adult. When Haruki used his first salary to gift her an onsen trip, Chisato felt profound joy. Yet, she also seemed to feel a quiet loneliness, as if her role as a mother had come to an end. It was a bittersweet emotion, intertwined with love, gratitude, and a touch of sadness.