 He went on to teach natural sciences and zoology at Hōsei University, Meiji University, Seikei University, and Senshū University from 1920 till shortly before his death.In his obituary in the Proceedings of the Malacological Society of London, he was noted to be “without political interests and enthusiastically devoted to the study of mollusks.” His publications of note included a review of Japanese oysters, scaphopods, and a catalogue of Japanese shells with hand illustrated plates.Shintaro died on September 9, 1939 at age 55 at his home in Tōkyō after a short period of kidney failure.