Japan was the leading manufacture of airplane, especially air fighters till 1945.
The main companies which built the aircraft were Mitsubishi, Nakajima and Kawasaki.
After the WWII, Japan including these companies had to abandon the plants for making the aircraft. It was one of the purpose to demilitarize Japan and change to a democratic state but the biggest reason was that US and its allies thought Japanese military planes were too dangerous.
The engineers who worked hardly for their companies, thinking only the Japan's victory lost their jobs and had to move to the different industries. Some of the elite engineers moved to field of railway and later made the Shinkansen.
Nakajima has changed its name to Fuji heavy industry and started to make automobiles under a brand SUBARU. Fuji heavy industry changed its company's name to Subaru later in 2010s. Mitsubishi which was the rival company of Nakajima is now creating a civilian jet plane called MRJ. This roughly 100 seats airplane was the Mitsubishi's long dream to revive as the major aircraft manufacture.
Mitsubishi once dominated the sky of East Asia and the Pacific. Mitsubishi A6M fighter called ZERO was the one of the best fighter planes in the early WWII. Zero took off from Japanese Imperial Navy's aircraft carriers and escorted their bombers and attackers during the mission over Pearl Harbor on the morning of 07 December 1941. Due to its ultimate abilities, US generals told their pilots not to dog fight with ZERO. Zero overwhelmed the counterparts for its speed and the range. Then also Zero was the world's first fighter to equip with 20mm aircraft machine guns.
However, Zero was forced to be used as the Kamikaze at the end of the war. Young university students were drafted to the navy and forced to fly as the Kamikaze pilots. At that time, refuse to fly did not exist or pilot who refused to fly was blamed as NON-patriot. Everyone tried to die for the country and for the emperor.