The Otsukis have been married for 40 years, a lovey-dovey couple. After their son became independent and the husband retired, the couple spent the rest of their lives relaxing together. One day, their son gifted them a trip to a hot spring to celebrate their 40th wedding anniversary. But now that they think about it, they haven't even gone on a trip together since their son was born. Before they knew it, the couple had become sexless, and they felt more like partners sharing joys and sorrows than a relationship between man and woman...
