Kuniaki Koiso (1880-1950) was an Imperial Japanese Army general, Prime Minister of Japan between July 1944 and April 1945, and a Major War Criminal sentenced to life imprisonment by the International Military Tribunal for the Far East.
He was born to a samurai family in Yamagata Prefecture, graduated from the Military Academy, and served in the Russo-Japanese War. Graduating from the Military Staff College in 1907, he then taught at the Academy and had various general staff positions.
In 1930, he became director of the Military Affairs Bureau of the War Ministry, and was involved in planning the March 1931 Incident.  A member of the Control Faction, he moved through a series of increasingly senior positions, positions, including vice war minister, chief of staff of the Kanto Army (i.e., Tokyo area), chief of the 5th Division, and commander of the Korea Army, he was promoted to full general in 1937.
Subsequent positions included colonial affairs minister in the Hiranuma cabineto in 1939 and the governor-general of Korea in 1942. His ten years in Korea had isolated him from the mainstream of the army, leaving him a "snobbish, senile general on the reserve list, without any influence whatever in the Army."
Nevertheless, like his predecessor Hideki Tojo, he tried to unify Cabinet and General Headquarters into a unified command, by holding the posts of Prime Minister and Army Minister.
The Army refused to go along, and forced him out of office by refusing to put him back on the active list so he could become Army Minister. Aggravating the situation was the start of the Battle of Okinawa. He resigned on 5 April and was replaced by Kantaro Suzuki.
He was charged and convicted with participating in planning the Second Sino-Japanese War, and, as Prime Minister, failing to prevent atrocities but having command responsibility. He died in prison.
- War Responsibility--delving into the past (1) / Who should bear the most blame for the Showa War?, Yomiuri Shimbun
- Merion and Susie Harris (1991), Soldiers of the Sun: the Rise and Fall of the Imperial Japanese Army, Random House, p. 449
- Chairman's Office (1 July 1946), Japan's Struggle to End the War, United States Strategic Bombing Survey, p. 5
- Chapter V, Japanese Aggression Against China. Section I. Invasion & Occupation of Manchuria. The China War and Its Phases, International Military Tribunal for the Far East, pp. 536-537