Torpedo bombers. The Nakajima B6N "Jill" torpedo bomber incorporated considerable improvements over the Nakajima B5N "Kate" in speed and range but its introduction was delayed by development and production problems. By the time the Jill was introduced, the Allied thrust up the Solomon Islands caused IJN leadership, in late 1943, to transfer many carrier aircraft from their first line carriers to land-based service out of Rabaul. With the Allies having firmly established air superiority in the area, only a fraction of these planes made it back to their carriers two weeks later. In the following year, carrier-based Jills suffered huge losses at the Battle of the Philippine Sea in mid-1944. With so few IJN carriers remaining afloat after the Battle of Leyte Gulf, the Jills became mostly land-based and by early 1945 were in use as "kamikazes".