The Yokusan Sonendan (大日本翼賛壮年団 Imperial Rule Assistance Young Men's Corps) was an elite para-military youth branch of the Imperial Rule Assistance Association political party of wartime Empire of Japan established in January 1942, and based on the model of the German Sturmabteilung (stormtroopers).
Members received a deep political indoctrination and basic military training. Their responsibilities included forming part of the home guard to assist in matters of civil defense under the direction of official local authorities. They were issued mostly obsolete weapons provided to the organization under orders from their Director-General Kingoro Hashimoto, and were intended to assist local efforts in fire fighting following air raids, distribution of emergency supplies and rendering basic first aid. The most advanced pupils were earmarked for eventual enrollment in the Imperial Japanese Army Academy, or for a future role as elected local politicians within the Taisei Yokusankai organization.
In addition to its civil defence and para-military role, the Yokusan Sonendan was also tasked with assisting the local tonarigumi organizations and the Kempeitai in watching for any signs of subversive ideologies in their local areas and reporting any anti-war or anti-government activities.
In the last stages of World War II, the members receiving additional military training in the use of anti-tank weapons and light machine guns, for conversion into reserve combat units to support Japan's remaining troops against the projected invasion of the Japanese homeland by the Allies. The group suffered heavy combat casualties during the Battle of Okinawa. The Yokusan Sonendan was disbanded on 30 May 1945  and its membership merged into the Volunteer Fighting Corps.
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