When his daughter-in-law was hospitalized after a difficult birth, his mother-in-law came to Tokyo from the countryside out of concern. The son-in-law was happy that his mother-in-law had come all the way, but in fact, he had an ulterior motive for her. One night, he had an affair with his mother-in-law, promising that it would only be once. After living with his mother-in-law for a while... something will happen!?