Columbia subject headings:
Intelligence service--Japan--History.
Japan--Politics and government--1600-1868.
Secret service--Japan--History.
Harvard subject headings:
Intelligence service--Japan--History.
Japan--Politics and government--1600-1868.
Secret service--Japan--History.
Princeton subject headings:
Intelligence service--Japan--History.
Japan--Politics and government--1600-1868.
Secret service--Japan--History.