My father remarried and my new mother, Sayuri, came to live with me. At the same time, I went to college outside of the prefecture and ended up living alone in a boarding house without having much to talk to Sayuri. When I returned home for winter break, my parents and I decided to hold a Christmas party together... As the two of us drank, we fell asleep in the kotatsu table, and I accidentally kissed Sayuri's defenseless lips. At that moment, I was overcome by a pleasure that made my whole body melt...