The Nakajima Ki-27 was the most common fighter aircraft in the JAAF until 1940. In 1939, during the Battle of Kalkhin Gol (Nomonhan) against the USSR, the Ki-27 faced Polikarpov I-15 biplanes and Polikarpov I-16.
The Ki-43 Hayabusa "Oscar" was a fighter of the JAAF during World War II. Almost 6000 were built. The Ki-27 being transferred to the Mansyu factory at Harbin in Japanese occupied Manchukuo.