In 1937, prior to World War II, Lieutenant Colonel Yuuki founded the "D Agency," a military intelligence unit that fell under his leadership and guidance. To ensure the unit's effectiveness, Lieutenant Sakuma was appointed by the Army General Staff to oversee its operations. Unlike traditional Japanese military personnel, D Agency sought out suitable agents from various sources, and Yuuki introduced unorthodox principles to guide the unit, straying from IJA doctrine. The guiding principles were "Avoid killing, being killed, and being captured." Yuuki then proceeded to train a team of agents to undertake missions against domestic and foreign authorities.