Sayuri raised Tatsuya by herself after divorcing her husband 15 years ago. Because it is a single-mother family, he worked desperately not to make Tatsuya feel pity, took care of Tatsuya until he graduated from university, and decided his career after graduation. Tatsuya worked hard to live up to his mother's grace. Every day I go to work on the first train and return home on the last train, I can't take a day off. And finally one day Tatsuya broke. Sayuri invited Tatsuya to a hot spring to cure her.