He is a social and cultural historian of Japan, whose interests range from the fifteenth through the early twentieth centuries. A specialist in the history of the Ryukyu Kingdom and of the impact of earthquakes on society, he is the author of Visions of Ryukyu: Identity and Ideology in Early-Modern Thought and Politicsand co-editor with Bettina Gramlich-Oka of Economic Thought in Early-Modern Japan. He is the author of two studies of Japanese earthquakes: When the Earth Roars: Lessons From the History of Earthquakes in Japan and Seismic Japan: The Long History and Continuing Legacy of the Ansei Era Earthquakes.