(Scanned from "Submarines of the Imperial Japanese Navy" by Polmar and Carpenter)

Developed from the KD6 type, these attack submarines had an endurance of 75 days.  Differences from the earlier type include concentration of all tubes forward, and slightly improved operating depth.  The most notable naval successes by this class were both achieved by I-176.  I-176 damaged cruiser USS Chester off Guadalcanal on 2 October 1942, preventing her from participating in the Battle of the Eastern Solomons and the First Battle of Guadalcanal.  That boat also sank USS Corvina patrolling off of Truk on 16 November 1943.  Polmar and Carpenter state that was the only instance of a Japanese submarine sinking a US submarine.

Seven of these boats were sunk within one year after commissioning, and all ten of these boats were lost by October, 1944.  I-176, I-177, I-180, I-181, and I-185 were all sunk by American Destroyers in 1944, while I-182 had a similar fate a year earlier.  Also in 1943, I-178 became one of very few submarines sunk by a submarine chaser, and I-179 was lost when a hatch was left open during a training dive, less than a month after completion.  I-183 was sunk by USS Pogy (SS266) in home waters in April, 1944.  I-184 was sunk by depth bombs dropped by an aircraft from USS Suwanee on 19 June 1944.

These boats were originally numbered I-76, I-77, etc.  They were renumbered in 1942.