The Nakajima Ki-44 Shōki (鍾馗) ("Demon Queller") was a single-engine fighter aircraft used by the Imperial Japanese Army Air Force in World War II, first flying in August 1940 and entering service in 1942. The Allied codename was "Tojo"; the Japanese Army designation was "Type 2 Single-Seat Fighter" (二式単座戦闘機).

In contrast to its predecessor, the nimble Ki-43, the Ki-44 was designed for speed and climbing ability and was used to intercept high-flying B-29 Superfortress bombers. With its poor visibility on the ground, weak armament, and high landing speed, it was generally disliked by pilots.

The pre-production Ki-44 aircraft and two of the prototypes were turned over to the Army for service trials on 15 September 1941. The type commenced operations with one experimental unit, the 47th Chutai (Independent Air Company) ("Kawasemi Buntai", Kingfisher Unit) sent to Saigon, Indochina in December 1941 with nine aircraft under the command of Major Toshio Sakagawa.

The unit later became the 47th Sentai, when flying home defense in Japan. More aircraft were later sent to China, and others were used in defense of oil wells in Sumatra, Indonesia, the China-Burma-India theater of operations, Philippines, Japanese metropolitan defense, mainly concentrated around Japan's large industrial cities and even kamikaze operations in the last stages of the war.

The 2c version "Tojos", armed with heavy cannon, were used against B-29s by one special kamikaze unit (a company of four aircraft minimum) of the 47th Sentai, which specialized in bomber collision tactics, the Shinten unit ("Shinten Seiku Tai"(Sky Shadow) 47th Sentai (Air Regiment) based at Narimasu airfield), during the defense of Tokyo.

The Nakajima Ki-44 at one point equipped 12 sentais of the Japanese Army Air Force (the 9th, 22nd, 23rd, 29th, 47th, 59th, 64th, 70th, 85th, 87th, 104th and 246th Air Regiments) which saw action before their (partial) replacement with Ki-84 Hayates for the final battles of the war. The Manchoukouan Air force also received some examples of these aircraft during wartime.

After World War II, the Nationalist Chinese 18th Squadron of the 12th Fighter Group was equipped with Ki-44s formerly of the 9th Sentai, which had disbanded in Nanking, and of the 29th Sentai, which had disbanded at Formosa and they participated in the Chinese Civil War. The People's Liberation Army Air Force managed to get hold of aircraft formerly belonging to 22nd and 85th Sentai, who had disbanded in Chosen, the Japanese name for Korea during their imperial rule (1910-1945) over that country. These aircraft were flown by Japanese nationalist pilots, who used them until the last two Ki-44s finally retired in the early 1950s.