Kasumi, who divorced her husband 10 years ago, raised her son on her own. She worked hard, raised him, and even after sending him to college, she worked hard to pay for his tuition. Thanks to all that, her son got a job offer from a major staffing agency. Just when she thought that her child-rearing was over, she felt a hole in Kokoro. While she was feeling lonely, her son invited her on a hot spring trip, and the two of them set off on their graduation trip.