Ever since Masaaki's father died in an accident when he was young, Aoi has been raising him single-handedly. Masaaki never had a rebellious phase, but he grew to love Aoi, who had always loved him wholeheartedly, more than a mother. One day, Aoi invited Masaaki on a trip to a hot spring. She felt that she had not been able to do anything for him as a parent, and wanted to make it their last memory together. Masaaki had a bad idea about the invitation. "I wonder if I can hold my mother in my arms on this trip."