Dutch East Indies campaign
Shimakawa was a member of the Tainan Air Group at the beginning of the Pacific War. Often assigned as a wingman to legendary ace Saburō Sakai, Shimakawa fought in the conquest of the Philippines and the Dutch East Indies campaign. In April 1942, Shimakawa was transferred to the aircraft carrier "Kaga's" fighter group, with which he participated in the Battle of Midway.