He attended Hibiya High School and graduated from the University of Tokyo.
He joined the Ministry of Foreign Affairs in 1959.
He was an adviser to the Imperial Household Agency from 2012 on.
He was strongly opposed to the publication of the book Princess Masako: Prisoner of the Chrysanthemum Throne in 2007 and said the Imperial Household Agency could not accept it.
[1] Watanabe died on 8 February 2022, at the age of 85.