Japan
Despite having some of the best machine guns, bombs, and tanks of that era, one particular entity stood out from the rest – the Japanese aircraft. Between 1935 and 1945, the Japanese military selected the best high-tech companies such as Mitsubishi and Nakajima Aircraft Company, tasking them with the development of the best fighter aircraft prototypes of that time.
As a result, well over 48 different fighter plane models were developed in just under a decade, some of which were abandoned as prototypes.