(Scanned from Polmar & Carpenter 's "Submarines of the Imperial Japanese Navy")

Authorized in the "First Replenishment Program" of 1931, the Type J2 was similar to the Type J1M, except in having more powerful engines, a slightly longer hull, and somewhat less range.  The Type J2 definitely had a catapult aft, with the aircraft being launched astern.

The I-6 was the only ship of this type, but she was very active.  Patrolling off Oahu at the start of the war, she damaged aircraft carrier USS Saratoga on 11 January, 1942, removing that valuable warship from the US Pacific Fleet's roll call for a very critical six month period.  I-6 made one patrol off the coast of Java in early 1942, then performed reconnaissance off the western coast of India in April 1942.  She sank two cargo vessels in each of these missions, including 5,897-ton Clan Ross and the 5,424-ton Bahadar off Bombay.  She patrolled Aleutian waters in late 1942, then laid mines, including six acoustic mines received from Germany, off Brisbane, Australia on 13 March 1943.  Allied naval intelligence knew of this mission in advance  Three American submarines waited in ambush, but none sighted I-6 that night.

I-6 was sunk in a collision with the freighter TOYOKAWA MARU on 16 June 1944.