No other Japanese aircraft surpasses the Mitsubishi A6M Reisen ("ree-sin") as the symbol of Japanese air power during World War II. All Allied pilots feared and respected the Zero fighter early in the war. After 1942, better Allied training and tactics, superior aircraft, and the loss of experienced Japanese pilots made the Zero much less formidable. Jiro Horikoshi, Chief Engineer at Mitsubishi Jukogo K. K., designed the Zero Fighter but both Mitsubishi and Nakajima produced the airplane. The two companies built 10,449 Zeros between March 1939 and August 1945-more than any other Japanese aircraft.

Mitsubishi developed the Zero 63 to fill a gap in dive-bombers that developed late in the war. The Yokosuka D4Y Suisei (Comet) JUDY dive bomber entered series production in the spring of 1943 (replacing the obsolete Aichi D3A VAL used at Pearl Harbor). The bomber proved too large and landed too fast to operate from small-deck aircraft carriers. By late 1944, following tremendous defeats at Midway, the Philippine Sea, and Leyte Gulf, Japan's large-deck carrier fleet was almost wiped out. Dive bombers that could operate from small flight decks were urgently needed. When the Navy directed Mitsubishi to redesign the Zero to drop bombs, the A6M7 was born. The centerline fuel tank was replaced with a bombrack that carried a single 250 kg (551 lb) bomb. The horizontal stabilizer was reinforced to withstand the stress of pulling-out from a steep dive, and hardware was installed in the wings to carry two 150-liter (40 gal) drop tanks. Production began in May 1945.

No other aircraft surpasses the Mitsubishi A6M Reisen ("ree-sin," Japanese for Zero Fighter) as the symbol of Japanese air power during World War II. Mitsubishi designed the Zero fighter but co-produced the airplane with Nakajima. The two companies built more than 10,000 Zeros between March 1939 and August 1945. Design work began in 1937 when the Japanese Navy staff directed Mitsubishi and Nakajima to submit proposals for a new aircraft to replace the Mitsubishi A5M carrier fighter (Allied codename CLAUDE). Combat trials began in China during July 1940 and by fall, Zero pilots's felled nearly 100 Chinese aircraft for the loss of only two Zeros to friendly fire.

Japanese naval aviators flew 328 combat-ready A6M2 Reisens against American forces at Pearl Harbor and in the Philippines. The Reisen totally outclassed all Allied fighter aircraft for the first six months of the war until American carrier forces stopped the Japanese in the Coral Sea and at Midway in May and June 1942. The loss of four Japanese aircraft carriers at Midway underscored a deadly trend. The Japanese were losing experienced pilots and aircraft faster than they could replace them. Yet for almost two more years the ZEKE, as the Allies code-named it, remained an ominous threat.

Key to the Zero's potent performance was weight. In May 1937, the Japanese naval staff issued preliminary specifications for a fighter to fly from aircraft carriers. To satisfy these demanding requirements, Mitsubishi designer Jiro Horikoshi and his team focused specifically on reducing airframe weight as much as possible. Horikoshi used a new lightweight aluminum alloy developed in Japan and he chose to omit armor plate and self-sealing fuel tanks from the design. These protective devices weighed hundred of kilograms and could not be incorporated if Mitsubishi hoped to meet the performance requirements specified by the navy. Yet, the lack of these components eventually became the Zero's undoing.

The Reisen was considerably lighter than American fighters. It could climb faster and out-maneuver them in close combat or 'dog fighting.' However, as combat experience mounted and training improved, the American tactics began to change. U. S. Navy and Army pilots avoided the turning and looping dogfight and began to engage the Zeros only when they could surprise the Japanese pilots by attacking with a height or speed advantage. This type of attack consisted of a single, straight pass with guns blazing. The American pilot then continued away from the Zero using his superior speed to zoom to safety or circle around at a distance and attack again. This idea and other tactics transformed pilots flying the Grumman F4F Wildcat (once considered totally obsolete against the Zero) into formidable opponents more than capable of destroying the Japanese fighter.

The Allies began fielding aircraft superior to the Zero in 1942. Lockheed chief designer, Kelly Johnson, crafted the airplane that eventually destroyed more Japanese aircraft than any other, the Lockheed P-38 Lightning. U. S. Army Air Forces Lightning pilots downed the first Zeros late in 1942, using their superior speed and climbing performance. The F6F-3 Hellcat entered combat in August 1943 and the Pratt & Whitney R-2800 engine that propelled it also gave the Hellcat pilot enough speed and climb to engage or avoid the Zero without regard for the tactical situation.

Japan's aviation industry continued to develop advanced fighters but a number of problems plagued the complex process of perfecting and fielding these new airplanes and only limited numbers saw action. Consequently, the Zero remained in production throughout the war. The Japanese built 11,291 Zeros and sub-variants related to it, more than any other Japanese warplane.

Mitsubishi developed the Zero 63 to fill a gap in dive-bombers that developed late in the war. The Yokosuka D4Y Suisei (Comet) JUDY dive bomber entered series production in the spring of 1943 (replacing the obsolete Aichi D3A VAL used at Pear Harbor). The bomber proved too large and landed too fast to operate from small-deck aircraft carriers. By late 1944, following tremendous defeats at Midway, the Philippine Sea, and Leyte Gulf, Japan's large-deck carrier fleet was almost wiped out. Dive bombers that could operate from small flight decks were urgently needed. When the Navy directed Mitsubishi to redesign the Zero to drop bombs, the A6M7 was born. The centerline fuel tank was replaced with a bombrack that carried a single 250 kg (551 lb) bomb. The horizontal stabilizer was reinforced to withstand the stress of pulling-out from a steep dive, and hardware was installed in the wings to carry two 150-liter (40 gal) drop tanks. Production began in May 1945.

The NASM A6M7 was among about 145 captured Japanese aircraft shipped to the U. S. from the Yokosuka, Japan, area in October-November 1945. The fighter bomber was probably based at Misawa, a testing facility operated by the First Naval Air Technical Bureau (abbreviated Kugisho in Japanese, equivalent to the U. S. Navy Bureau of Aeronautics). After tests were carried out in the United States, the Navy exhibited the airplane outdoors at Naval Air Station Willow Grove, Pennsylvania, for many years. NASM acquired the aircraft from Willow Grove on March 3, 1962, then lent it to the Bradley Air Museum in Windsor Locks, Connecticut, for restoration. Bradley technicians did not complete the project before the aircraft was transferred to the San Diego Aero-Space Museum were a volunteer crew spent more than 8,500 man-hours restoring the airplane. It remains on exhibit in San Diego.