He is a professor of marine seismology at Earthquake Research Institute, the University of Tokyo. His research into earthquake generation at plate boundaries and structures below the sea have contributed to the development of new observation apparatuses in the marine environment. He developed the practical digital-recording pop-up-type ocean bottom seismometer (OBS) in early 90s and has worked in the development of the long-term OBS which can record continuously more than one-year on seafloor and the broadband OBS which has high-performance broadband seismic sensor. (SATREPS).