The Ki-61 was designed by Takeo Doi and his deputy Shin Owada in response to a late 1939 tender by the "Koku Hombu" for two fighters, each to be built around the Daimler-Benz DB 601Aa. Production aircraft would use a Kawasaki licensed DB 601, known as the "Ha-40", which was to be manufactured at its Akashi plant. The Ki-60 was to be a heavily armed specialised interceptor, with a high wing loading; the Ki-61 was to be a more lightly loaded and armed general-purpose fighter, intended to be used mainly in an offensive, air superiority role at low to medium altitudes.