He was promoted to captain in 1930, and to rear admiral in 1936, serving in various administrative posts. Having reached the rank of vice admiral on 15 November 1940, Ishii was made director of the Maizuru Navy Yards, overseeing ship construction.
He was elevated to captain in 1930, and to rear admiral in 1936, holding various administrative positions. Upon achieving the rank of vice admiral on November 15, 1940, Ishii was appointed director of the Maizuru Navy Yards, overseeing ship construction.