The Arisaka Type 99 was the primary infantry weapon of the Imperial Japanese Army during World War II. Although it was intended to replace the older, less powerful Type 38, the complications of war led to both rifles seeing widespread use. The Type 99 was produced between 1939 and 1945 by a variety of arsenals in Japan, several abroad, and by many civilian manufacturers such as Toyo Kogyo. It utilizes a simple bolt action heavily based on the Mauser design, but stronger. All Type 99s manufactured for military use are identified by kanji for "Type 99" stamped into the receiver, along with a 16-petal chrysanthemum. Rifles for police use or training may have different markings.
When the Type 99 was designed, the Japanese military was disappointed in the performance of the 6.5x50mm cartridge used in the Type 38. It lacked power compared to the .303 British or the American .30-06. For the Type 99, they introduced the 7.7x58mm round, also known as 7.7 Arisaka or 7.7 Japanese. The new ammunition was the equal of its western counterparts, with the same caliber as the .303 in a rimless case. Unrelated to 7.7 Arisaka, the Japanese also produced many rimmed 7.7 cartridges. These rounds were copies of the .303 British for use in copied Vickers machine guns, and will not chamber in a Type 99.
Over the course of the war, the manufacture of the Type 99 changed considerably. Rifles produced early, when Japan controlled much of the Pacific theater, had many accessories lacking on later models. They included folding steel monopods in the stock and bolt covers to keep sand and dirt out of the action. Most also had anti-aircraft sights consisting of a folding iron sight with hinged bars on each side. The AA sight was intended to help the Japanese infantryman draw a bead on enemy aircraft. Rifles made during the first half of the war also had more decorative features, including oval bolt handles and safety knobs machined with knurling for better grip.
After the battle of Midway, as Japan became more pressed for resources, rifles were produced lacking many of the earlier features. Parts such as bolt handles and safety knobs were welded together instead of being carefully machined. Unneccessary items such as the flip-up sights or folding monopod were left off altogether. Rifles produced during the last two years of the war, known colloquially as "last ditch" guns, may even be dangerous to fire. These rifles were produced with lower-quality steel and were not subjected to the heat treating that earlier models received. There are even reports of Type 99s with smoothbore barrels which never received rifling. Many of the worst examples were produced prior to the surrender of the Japanese and have never seen combat; they may not even be capable of firing a shot.
While not as common as the Soviet Mosin-Nagant or German Mauser rifles, many Type 99s survive today. Most were captured by Allied troops, or surrendered by the crate in 1945. The circumstances surrounding the rifle's change of ownership can often be deduced from the condition of its identifying chrysanthemum. One of the final orders of the Imperial Japanese Army was that the chrysanthemum, symbol of the emperor, be removed from all equipment prior to surrender. As a result, weapons formally surrendered to the Allies have the 'mum obliterated from the receiver. The American military, particularly Douglas MacArthur, supported this measure and ordered all personnel in possession of Japanese weapons to destroy the marking. Therefore, most late-war captures have token scratches through the flower, but leave it clearly visible. In general, only rifles captured early in the war have complete chrysanthemums.