A Diplomat in Japan, subtitled “The inner history of the critical years in the evolution of Japan when the ports were opened and the monarchy restored, recorded by a diplomatist who took an active part in the events of the time, with an account of his personal experiences during that period” is a book by Ernest Mason Satow, British scholar, diplomat and Japanologist, based mainly on his diaries. The book describes the years 1862–1869 when Japan was changing from rule by the Tokugawa shogunate to the restoration of Imperial rule.