Like Osaka, Kyoto and other important cities, Nagasaki was governed by a shogunate-appointed magistrate who was responsible for civil and judicial administration. The magistrate of Nagasaki was the executive organ of shogunate authority in western Japan and exercised influence over the entire region. The magistrate had five main duties covering a wide range of issues: First, the civil and judicial administration of Nagasaki. Second, identifying and purging the hidden Christian population of western Japan. Third, commanding the daimyo lords of western Japan in matters involving defense against foreign ships. Fourth, regulating foreign trade. And fifth, controlling smuggling.
The Restoration of the Nagasaki Magistrate's Office