The Nakajima Ki-62 was a design for a fighter to be powered by the Japanese version of the Daimler-Benz DB 601A engine, produced in case the Kawasaki Ki-61 design failed.
Kawasaki had purchased the rights to build the DB 601A engine in Japan, where it was given the designation Ha-40. They were then (1940) ordered to design two fighters based around this engine, the heavy interceptor Ki-60 and the general purpose Ki-61. By this date the Japanese Army Air Force had abandoned competitive tendering, and instead commissions a single company to produce each new design, but it had been some time since Kawasaki had produced a fighter for the army.
The last three army fighters (the Ki-27, Ki-43 and Ki-44) had been Nakajima products, and they were now asked to produce their own design for a fighter based around the Ha-40, as a back-up in case the Ki-61 failed. A design team led by T. Koyama was set up, and during 1941 they produced designs for both the Ki-62 and a radial-engined version, the Ki-63.
The Ki-62 was very similar to the Kawasaki Ki-61, with the same droopy nose as seen on most DB 601 powered aircraft (including the Bf 109). The Ki-62 differed in having a cut-down rear fuselage and a bubble cockpit canopy, which would have provided better visibility than the faired-in cockpit used on the Ki-61. The air intake for the radiators was also in a different position, just in front of the wing, while that on the Ki-61 was behind the wing.
Once it was clear that the Ki-61 was going to be a success work on the Ki-62 and Ki-63 came to an end. Instead Nakajima were asked to produce a new all-purpose fighter which would have much more in common with Allied designs than with earlier Japanese aircraft, emphasising speed, protection and firepower instead of manoeuvrability. T. Koyama and his team began work on the new Ki-84 early in 1942, using many features developed for the Ki-62.