Kuniaki Koiso
Satō was born in Yamagata prefecture and attended military preparatory school in Sendai. He graduated from the Imperial Japanese Army Academy in 1913 and the Army Staff College in 1921, and was assigned to administrative duties within the Imperial Japanese Army General Staff. He spent two years as the head of the War History Bureau, during which time he came into contact with many important members of the "Tōseiha" political faction within the Army, including Kuniaki Koiso and Hideki Tōjō, and was involved in the creation of the Sakurakai organization with Kingoro Hashimoto. Also during this period, he had serious conflicts with the head of the General Affairs section of the General Staff Renya Mutaguchi, who also happened to be a staunch supporter of the rival "Kōdōha" faction. he was promoted to lieutenant colonel in December 1932 and assigned to the IJA 11th Infantry Regiment. From August 1934, he was assigned to the staff of the IJA 6th Division. During the February 26 incident, IJA 6th Division played a role in the suppression of the pro-"Kōdōha" attempted coup-d'etat.