Astronomer. After graduating from the Department of Physics of the Imperial University of Tokyo, he became a professor at the Army Artillery and Engineer School, then later an assistant professor at the Department of Science and Technology of the Imperial University of Kyoto. He also established the Department of Astronomy at the Imperial University of Kyoto and served as its president from 1929. In his later years, he served as director of the Shanghai Natural Science Research Institute. Although he is known for his research on physical cosmology, his investigations also extended to the calendrical sciences in ancient China, and he gained renown as a scholar of East Asian astronomy. He authored many works, including Toyo Tenmongakushi kenkyu (Studies in the History of East Asian Astronomy). He also actively worked to debunk folk divination practices.