Rear-Admiral Kyuji Kubo was Commander of the 4th Surprise Attack Force.

On 12 December 1941, on board the light cruiser flagship Nagara, he led the invasion force at the Luzon, Philippines landing.

On 08 November 1942, again using the cruiser Nagara as his flagship, he was Commander of Escort Group (2nd Destroyer Flotilla) during the invasion of Makassar in Celebes.

From 19 to 20 February 1942, as Commander of Bali Occupation force he was involved in a naval battle with the ABDA (American British Dutch Australian) naval forces of Dutch Admiral Karel Doorman, off the coast of Bali Island.

Aboard the light cruise flagship Naka, he was the Commander of the Christmas Island invasion, 190 miles southwest of Java, on 31 March 1942.