Mr. and Mrs. Da Yue have been married for 40 years and love each other as much as ever. Their son lives independently, and after her husband retires, they spend the rest of their lives together. One day, to celebrate their 40th wedding anniversary, their son gave them a trip to a hot spring. Come to think of it, they hadn't even traveled together since the birth of their son. Without realizing it, their sex life has become boring. Instead of being boyfriend and girlfriend, they are more like companions who share the same pain...