It was designed by the
Kyūshū Aircraft Company to the 14-Shi Intermediate Trainer specification of mid-1939, which required a design similar to the
North American NA-16 following the Mitsubishi's purchase of an NA-16-4R and an NA-16-4RW on behalf of the Japanese Navy. Design work commenced in January 1940, and the first prototype was ready by April 1941. Despite the similarity of the K10W to other contemporary Japanese aircraft, such as the
Tachikawa Ki-55 and
Mitsubishi Ki-51, it suffered from stall and stability problems that resulted in sixteen pre-production testing aircraft being built. Work at Kyuhsu on the
Q1W maritime patrol bomber and
K11W carrier crew trainer were given a higher priority. Kyūshū would build only nine production aircraft before production was transferred in 1943 to
Nippon Hikōki (a small company that did a lot of subcontract work), who, in turn, built 150 examples before production ended in August 1944. The Japanese had purchased two NA-16's, and Western sources have long believed that the K10W1 was a development of these. However, a close study of the "Oak", as it was code named by the Allies, shows that they shared nothing beyond a similar configuration. In addition, controls were run internally, and footrests retracted rather than being fixed. A version of the K10W built from wood was planned as the K10W2 but was never built. ==Operational service==