Ki-64 was an experimental heavy fighter prototype. It had two unusual design features; it had two Kawasaki Ha-40 engines in tandem; one in the aircraft nose, the other behind the cockpit, both being connected by a drive shaft. This combination (called the Kawasaki Ha-201) drove two, three-bladed, contra-rotating propellers. The aircraft first flew in December 1943. During the fifth flight, the rear engine caught fire; and while the aircraft made an emergency landing, it was damaged. The aircraft was subsequently abandoned in mid-1944 in favour of more promising projects.