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-73
"I-73" participated in the attack on Pearl Harbor as part of the 3rd Submarine Squadron in the 6th Fleet of the IJN. It was one of the vessels created as part of Japan's 1st Naval Armaments Supplement Programme in 1931. On 27 January 1942, "I-73" became the first warship to be sunk by a United States Navy submarine; USS "Gudgeon" fired three torpedoes at "I-73" and destroyed it. "Gudgeon" claimed that the torpedoes only damaged "I-73", but Station HYPO confirmed the loss.