The Ki-61 Hien was the only liquid-cooled Japanese fighter plane that was used during the Pacific War. As a result of efforts to reduce air resistance and weight, it was completed as a well-balanced aircraft that maximized both speed and maneuverability , and was officially adopted in 1943.
However, the lack of basic industrial strength led to poor production, and
the malfunction of the Ha-40 liquid-cooled engine due to a lack of maintenance skills was a weakness of this machine.
Nevertheless, they achieved success in the Philippines, New Guinea, and in the air defense of the homeland. In particular, during the air defense of the homeland , they maintained a high operational rate thanks to
a stable supply of parts and the efforts of veteran maintenance personnel, and because they had better high-altitude performance than other Japanese aircraft, they fought bravely against the B-29s.
In particular, the 244th Air Squadron, led by the youngest squadron commander in the history of the Army, Captain Teruhiko Kobayashi, fought fiercely and shot down over 160 B-29s by the end of the war, making it the best unit in the history of the war.
