Ryo, who divorced her husband 10 years ago, raised her son on her own. Not wanting to let her son have to sleep, she worked hard, and thanks to her efforts, her son went on to graduate school and got a job. Although her child-rearing career was coming to an end, Ryo was hit by a sense of loss. Then her son invited her on a hot spring trip. Ryo set off on a graduation trip just for the two of them...