He was commissioned an ensign in April 1932, received his wings in November 1933 as a naval aviator, and was promoted to sub-lieutenant in the same month.

[3] Promoted to lieutenant-commander in October 1941, Okumiya served throughout World War II, including on the aircraft carrier Ryūjō and with the 2nd Air Fleet of the Imperial Japanese Navy.

He returned to active duty in July 1957 with the rank of colonel, and was appointed commander of the air base at Utsunomiya.

He was promoted to major general in February 1958 and served as deputy head of Personnel and Training from August 1959 to April 1960.

He co-wrote with Mitsuo Fuchida Midway: The Battle that Doomed Japan; the Japanese Navy's Story, published 1955.