Ki-43-II Oscar
Hasegawa

The Nakajima Ki-43 Hayabusa (Peregrine Falcon) was a single-engine land-based tactical fighter used by the Imperial Japanese Army Air Force in World War II. The Army designation was "Army Type 1 Fighter; the Allied reporting name was "Oscar", but it was often called the "Army Zero" by American pilots because its certain resemblance to the Mitsubishi A6M Zero, the Imperial Japanese Navy's counterpart to the Ki-43. Both aircraft had generally similar layout and lines, and also used essentially the same Nakajima Sakae radial engine, with similar round cowlings and bubble-type canopies (the Oscar's being distinctly smaller and having much less framing than the A6M). While relatively easy for a trained eye to tell apart with the "finer" lines of the Ki-43's fuselage — especially towards the tail — and more tapered wing planform, in the heat of battle, and given the brief glimpses and distraction of combat, Allied aviators frequently mistakenly reported having fought "Zeros" in areas where there were no Navy fighters.

Like the Mitsubishi-produced A6M Zero, the radial-engined Ki-43 was light and easy to fly and became legendary for its combat performance in East Asia in the early years of the war. It could outmaneuver any opponent, but did not have armor or self-sealing tanks, and its armament was poor until its final version, which was produced as late as 1945. Allied pilots often reported that the nimble Ki-43s were difficult targets but burned easily or broke apart with few hits. In spite of its drawbacks, the Ki-43 shot down more Allied aircraft than any other Japanese fighter and almost all the JAAF's aces achieved most of their kills in it.

Total production amounted to 5,919 aircraft. Many of these were used during the last months of the war for kamikaze missions against the American fleet.