The technicians of the 9th Military Technical Research Institute, known as the Noborito Research Institute, toiled in the shadows of the Second World War to develop spy gear and special weapons for the Imperial Japanese Army (IJA). Their espionage devices, including secret inks, bugging devices, and miniature cameras, helped the Army’s dreaded Kempeitai and the shadowy Yama Agency counter foreign spies and track domestic dissent. Operatives of the IJA’s Nakano School for intelligence operatives and commandos took the equipment into the field with them. Noborito’s forgers reproduced...