The Ki-43 entered service with the Imperial Japanese Army Air Force with the designation Type 1 Fighter “Hayabusa” in late 1941 and served until the end of World War II. Model IIIa (Hayabusa San-gata Ko) was equipped with a tuned-up Nakajima Ha-115-II Sakae engine which produced 1230 KM and allowed for its maximum speed to reach 555 km/h at 6100 m.