Koichi and Fumi were always a close couple, but after the birth of their son and daughter, they rarely enjoyed their intimate life together. One day, they reunited with a friend from their university days and learned that the friend's married couple was deeply passionate about sex in their mature years. Inspired by this, Fumi and Koichi began reflecting on their own marriage. Now, they frequently take hot spring trips, where steamy encounters in the bath have become their shared pleasure. On this day, arriving at a secluded inn, the couple resolves to reignite the flame of their love with renewed passion.