Tadahiko joined the National Space Development Agency of Japan (present: Japan Aerospace Exploration Agency (JAXA)) in April 1993. After his work on the maintenance and operations of launch pad facilities at the Tanegashima Space Center, he was involved in the development of the JEM Exposed Facility and Pressurized Module, HTV Technical Demonstration Vehicle, and CALET. He was then involved in the conceptual study of a large geostationary satellite bus, and was engaged in the development of the Engineering Test Satellite 9 and large Hall thruster.