FSX Kawasaki Ki-100-I Ko. The Kawasaki Ki-100 was a fighter aircraft used by the Imperial Japanese Army in World War II. 275 Ki-100 airframes were built as Ki-61's before being modified to accept a radial engine in place of the original inline engine. The emergency measure of adapting a Ki-61-II-KAI fighter to carry a Mitsubishi radial engine resulted in one of the best interceptors used by the Army during the entire war. It combined excellent power and maneuverability and it performed better than most other IJAAF fighters. Upgrade to FSX by A.F. Scrub.