Mitsubishi Aircraft Company (Mitsubishi Kokuki) was the new name given by the Mitsubishi Company (Mitsubishi Shokai), in 1928, to its subsidiary, Mitsubishi Internal Combustion (Mitsubishi Nainenki), to reflect its changing role as an aircraft manufacturer catering to the growing demand for military aircraft in Japan.
Mitsubishi Nainenki had been established in Nagoya in 1920, and signed a technology agreement with Junkers in 1925. By 1926, it had become one the largest aircraft manufacturers in Japan with an output of 69 aircraft and 70 engines.
In 1932, Mitsubishi Aircraft was among the companies that involved in a consolidation process calalysed by the Imperial Japanese Navy's Aviation Arsenal. The Navy launched a three-year program to have the manufacturers develop certain types of aircraft under competition. Most important of them were the Mitsubishi A5M (96-Shiki) Carrier Fighter and Mitsubishi G3M (96-Shiki) Attack Bomber developed by Mitsubishi with engines made by Nakajima Aircraft Company. Introduced in 1936, it had a maximum speed of 450 km/h. The famous Mitsubishi A6M ("Zero") fighter was an improvement of the A5M and had a maximum speed of 500 km/h. Also well known was the Mitsubishi Ki-46 (100-Shiki) reconnaissance plane with a maximum speed of 540 km/h.
In 1934 the company was merged with Mitsubishi Shipbuilding to become Mitsubishi Heavy Industries (Mitsubishi Jukogyo). It had a prominent role to play in the upsurge of aircraft production in Japan, which shot up from 400 in 1931, to 4,800 in 1941 and peaked at 24,000 in 1944.