When Maki was 18, she became pregnant and gave birth to Tatsumei. Her father disappeared, and Maki single-handedly raised Tatsumei and put him through college. She was on good terms with her mother and daughter who were close in age, going shopping and traveling together. One day, Tatsumei invited Maki to a hot spring during his winter vacation. Maki was looking forward to her usual trip. However, Tatsumei had something he wanted to say to her when she was an adult, so he invited her on a trip...
