Yasuko felt growing dissatisfaction in her marriage and consulted her mother, Miho, but found no solution. Seeking to support her, Yasuko's husband, Ikuo, proposed a new idea: a hot spring trip together. On the day of the trip, hearing their constant laughter in an unusual atmosphere, Ikuo was nearly certain the getaway was a success. However, his true intention was to pursue a relationship with his mother-in-law, Miho. Sharing dinner and skillfully luring a slightly drunk Miho away, he led her into a separate room—setting his plan into motion.