Moreover the engine was not being produced in sufficient numbers. The initial version of the -II had a larger wing and a new canopy, but it was soon replaced by the -IIa with the older and proven wing. Only 374 of all variants of the -II were built. In early 1945 one of 275 engineless airframes was fitted with the Ha-112 radial engine. Although a sudden lash-up conversion this produced a staggeringly fine fighter, by far the best ever produced in Japan. This aircraft, designated the Ki-100, was put into production with desperate haste.