By the end of 1944 the Kawasaki factories 275 Ki.61-II airframes sitting around with engines to install , the engine (Ha.140 liquid-cooled) had lubercation system and fuel injection system probems, the maine bearing for the crankshaft were burning out...
The answer to the engine shortage was to convert the airframe to take a large - diameter air cooled radial (Ha.112-II) , the first of three convertion flew Feb 1, 1945, by May 1945 257 had be delivered and the Ki.100- Ib was being built as from the ground up, the only differing from the original model was the introduction of the all-around vision cockpit hood. Some 390 aircraft of all version were built...Note...this was the only JAAF in service single engined fighter that could holed formation above 30,000 ft.
