The protagonist was supposed to go on a hot spring trip with his wife...but ended up going alone with his wife's mother-in-law. I was worried about being alone with my mother-in-law, who I only see once a year when I go back to her parents' house, and who seems a little hard to get along with. And then we arrived at the hot spring inn. As they spend time together, their views on their step-moms change before they know it... This is a story of a step-mom and step-son who expose everything to each other and have sex with each other until morning.
