Initially a civilian project to break the world air speed record, it was taken over by the Imperial Japanese Army in 1941 and designated the Ki-78. The goal was to have the aircraft fly 528 mph / 850 kph.
The Aeronautical Research Institute at the University of Tokyo had a team led by Shoroku Wada that designed the aircraft. Mineo Yamamoto worked on the fuselage design, Eichiro Tani the wing, and Seichi Kurino and Shojiro Nomua the engine.
The wings had a laminar flow section to minimize resistance.
Due to the small wing size Fowler and split flaps were used for landings.
A Daimler-Benz DB 601A (1,175 HP) engine was installed. A first for Japanese aircraft, a water-methanol injection system was installed to allow boosts of power to 1,550 HP.
Radiators were installed on the fuselage sides to allow for more air cooling.