Ten years after her divorce, Tsubaki raised Kota with her own two hands. Refusing to succumb to the hardships of being a single parent, she worked tirelessly to ensure her son never felt pitiful. Before she realized it, Kota had reached the age of securing a job offer in the printing industry. With child-rearing finally complete, she felt a sense of relief, yet simultaneously lost her sense of purpose, drifting through empty days. One day, Kota suggested a hot spring trip, telling her, "Take a break from work once in a while and relax." Seeking warmth and relaxation, the two headed to a hot springs resort.