In autumn of 1937, as the coals of World War II are beginning to smolder, Lieutenant Colonel Yuuki of the Imperial Army secretly establishes a spy training organization called the "D Agency." Those chosen as members of the agency, in opposition to the national trend toward reverence of native-born soldiers in the army, are civilian university graduates who pass the superhuman selection test with flying colors. Under the resourceful Lieutenant Colonel Yuuki, they learn not only how to work with gunpowder, wireless communications, vehicles, and airplanes, but also various skills essential for spies, from pickpocketing to safecracking. "Don't die. Don't kill."
Suicide and murder are the worst possible options in the D Agency, which values a low profile above all else. Even as its agents bear under extreme opposition from the army's control center, they continue to betray allies, deceive foes, and conduct secret maneuvers all over the world. Tokyo, Shanghai, London... Their military intelligence reaches every last corner of the globe.