He joined the Electrical Communication Laboratories of NTT in 1970, where he engaged in the research and development of high-speed digital transmission systems using coaxial cable and optical cable including the WDM technologies, ATM systems, fiber-to-the-home systems, network management systems, and broadband network architecture. From 1992 to 1995, he was Executive Manager of the NTT Optical Network Systems Laboratories.
Since 1995, he is a Professor at the University of Electro-Communications, Tokyo, Japan, working in photonic network systems, wireless network systems and dependable network architecture.
He was one of founders of FSAN standardizaion forum, the Vice President of IEEE Communications Society in 1998 and 1999, and also the Vice President of IEICE in 2003 and 2004. Currently, he is the Chair of IEICE Standard Committee.