Kato, whose official title is ambassador extraordinary and plenipotentiary to the United States, was appointed to the ambassadorship in 2001. He previously served as Japan's deputy minister for foreign affairs from 1999-2001.

A longtime diplomat, Kato has been with the nation's ministry of foreign affairs office since graduating from Tokyo University in 1965. His career includes serving as director of the ministry's North American Affairs Bureau's Security Affairs Division, 1981-84; director of the Treaties Bureau's Treaties Division, 1984-87; minister of the Embassy of Japan in the U.S., 1987-1990; director of the General Affairs Division of the ministry's secretariat, 1990-92; deputy director general of the ministry's North American Affairs Bureau, 1992-94; consul general of Japan , San Francisco, 1994-95; director general of the ministry's Asian Affairs Bureau, 1995-97; and director general of the ministry's Foreign Policy Bureau, 1997-99.