Question: Operation Vengeance was designed to kill the leader of which Japanese military body?
Context: During World War II, it has been estimated that between 19,500 and 50,000 members of the Imperial Japanese military surrendered to Western Allied combatants prior to the end of the Pacific War in August 1945.  Soviet troops seized and imprisoned more than half a million Japanese troops and civilians in China and other places.  The number of Japanese soldiers, sailors, marines, and airmen who surrendered was limited by the Japanese military indoctrinating its personnel to fight to the death, Allied combat personnel often being unwilling to take prisoners, and many Japanese soldiers believing that those who surrendered would be killed by their captors. During World War II, the Commissione Italiana d'Armistizio con la Francia ("Italian Armistice Commission with France") or CIAF was a temporary civil and military body charged with implementing the Franco-Italian armistice of 24 June 1940 and harmonising it with the Franco-German armistice of 22 June.  It had broad authority over the military, economic, diplomatic and financial relations between France and Italy until the Italo-German occupation of France (Operation A) on 11 November 1942.  Thereafter its powers were gradually transferred to the Fourth Army, which was under the command of General Mario Vercellino and in occupation of southern France.  The headquarters of the CIAF was in Turin and it was subordinate to the "Comando Supremo" (Italian supreme command).  It liaised with the German Armistice Commission ("Waffenstillstandskommission", WAKO) in Wiesbaden. The Imperial Japanese Navy (IJN; Kyūjitai: 大日本帝國海軍 Shinjitai: 大日本帝国海軍 "   " or 日本海軍 "Nippon Kaigun", "Navy of the Greater Japanese Empire") was the navy of the Empire of Japan from 1868 until 1945, when it was dissolved following Japan's defeat and surrender in World War II.  It was controlled by the Imperial Japanese Navy General Staff and the Ministry of the Navy, both of which were nominally subordinate to the Emperor of Japan as supreme commander of the army and the navy.  The Japan Maritime Self-Defense Force (JMSDF) was formed after the dissolution of the IJN. Comfort bag (慰問袋, "imon-bukuro") was a gift packet prepared by civilians to be sent to Imperial Japanese Military soldiers for the purpose of encouraging them.  The bag contains comfort articles (慰問品, "imon-hin") not issued by the Japanese Military, such as toiletries, dried fruits, canned foods, and letters of encouragement.  Bags were prepared by schoolgirls or local patriotic women's societies.  These activities were also made in Korea, which was then under Japanese rule, to encourage Korean soldiers in the Imperial Japanese Military. Japanese invasion money, officially known as Southern Development Bank Notes (Japanese: 大東亜戦争軍票 "Dai Tō-A Sensō gunpyō", "Greater East Asia War military scrip"), was currency issued by the Japanese Military Authority, as a replacement for local currency after the conquest of colonies and other states in World War II.  In February 1942 in Japan, laws were passed establishing the Wartime Finance Bank and the Southern Development Bank.  Both institutions issued bonds to raise funds.  The former loaned money primarily to military industries, but also to a wide range of other ventures, including hydroelectric generators, electric power companies, shipbuilding and petroleum.  The latter provided financial services in areas occupied by the Japanese military, and Southern Development Bank notes were in fact used as de facto military scrip.  In December 1942, the outstanding balance of Southern Development Bank notes stood at more than 470 million; in March 1945, more than 13 billion. John William Mitchell (14 July 1915 – 15 November 1995) was an officer of the United States Air Force, a flying ace and the leader of Operation Vengeance, the mission to shoot down Admiral Isoroku Yamamoto.  He served in World War II and the Korean War. Military Factions (軍閥 , Gunbatsu ) is a Japanese language term having two separate meanings.  It is used to refer in the Japanese military in general, when it competed against the civilian leadership for control of the government’s domestic and foreign policy in the pre-World War II Empire of Japan.  It is also used to refer to political factions or cliques within the Japanese military itself.  The term came into common use in the Taishō period (1912-1926). The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well.  Every Japanese code was eventually broken, and the intelligence gathered made possible such operations as the victorious American ambush of the Japanese Navy at Midway (JN-25b) and the shooting down of Isoroku Yamamoto in Operation Vengeance. Operation "Vengeance" was the American military operation to kill Admiral Isoroku Yamamoto of the Imperial Japanese Navy on April 18, 1943, during the Solomon Islands campaign in the Pacific Theater of World War II.  Isoroku Yamamoto, commander of the Combined Fleet of the Imperial Japanese Navy, was killed on Bougainville Island when his transport bomber aircraft was shot down by United States Army Air Forces fighter aircraft operating from Kukum Field on Guadalcanal. The Sasanian army (Middle Persian "Spâh-ī Sāsānīg") was the primary military body of the Sasanian armed forces, serving alongside the Sasanian navy.  The birth of the army dates back to the rise of Ardashir I (r. 224–241), the founder of the Sasanian Empire, to the throne.  Ardashir aimed at the revival of the Persian Empire, and to further this aim, he reformed the military by forming a standing army which was under his personal command and whose officers were separate from satraps, local princes and nobility.  He restored the Achaemenid military organizations, retained the Parthian cavalry model, and employed new types of armour and siege warfare techniques.  This was the beginning for a military system which served him and his successors for over 400 years, during which the Sasanian Empire was, along with the Roman Empire and later the East Roman Empire, one of the two superpowers of Late Antiquity in Western Eurasia.  The Sasanian army protected "Eranshahr" ("the realm of Iran") from the East against the incursions of central Asiatic nomads like the Hephthalites and Turks, while in the west it was engaged in a recurrent struggle against the Roman Empire.
Answer: Imperial Japanese Navy