6th Fleet (Imperial Japanese Navy)
Despite these advantages, IJN submarines achieved remarkably little during World War II primarily having in hindsight suffered from the antiquated strategy of the Imperial Japanese Navy General Staff, who viewed submarines as little more than scouts whose main role was to locate and shadow enemy naval task forces in preparation for a decisive surface conflict. Maybe the IJN General Staff was slow to change as the submarines were generally slow to dive, easy to track with radar and sonar, difficult to maneuver underwater, and less sturdy than their German U-boat counterparts.
History of submarines
On 14 June 1904, the Imperial Japanese Navy (IJN) placed an order for five Holland "Type VII submersibles", which were built in Quincy, Massachusetts at the "Fore River Yard", and shipped to Yokohama, Japan in sections. The five machines arrived on 12 December 1904. Under the supervision of naval architect Arthur L. Busch, the imported "Hollands" were re-assembled, and the first submersibles were ready for combat operations by August 1905, but hostilities were nearing the end by that date, and no submarines saw action during the war.