When Asaka was 18 years old, she became pregnant and gave birth to the child of her senior at university. After that, her university seniors lost contact, leaving Asaka to raise her son Masaaki alone. Masaaki, who grew up watching his mother, who went on to college while working as a nurse, grew up to be a good and serious child. Such a son also graduated from college and got a job. Wanting to spend the remaining time together slowly, Masaaki uses the money he saved from his part-time job to take Asaka on a trip to the hot springs.
