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.
Japanese submarine I-8
The Japanese submarine "I-8" was a World War II Junsen Type J-3 Imperial Japanese Navy submarine. The vessel, along with "I-7", were the largest Japanese submarines to be completed before the outbreak of the Pacific War. It was based on the KD ("Kaidai") type. Both submarines participated in the attack on Pearl Harbor, they also conducted patrol missions with Yokosuka E14Y seaplanes.
In 1943 "I-8" completed a technology exchange mission by sailing to German occupied France and back to Japan. Under a new commander later in her career, the submarine's crew committed several war crimes in the latter period of the second world war.