This was the rifle Japan used against Marines in WW2
The average Japanese infantryman was a highly-trained soldier. That said, some of his weapons weren’t exactly the best in the world. While the United States gave its troops a classic rifle in the form of the M1 Garand, Japanese troops were left with a somewhat obsolete bolt-action rifle known as the Arisaka.
According to ModernFirearms.net, Japanese troops used two primary types of the Arisaka. The first was the Arisaka Type 38, which first entered service in 1906 after the Russo-Japanese War. The rifle was chambered for a 6.5x50SR cartridge and had an internal five-round magazine. According to MilitaryFactory.com, Japan bought about 3.4 million of these rifles over the years, an impressive production run. The British, Thais, Chinese, and Russians also used that rifle at one point or another.
Japan had a good reason to pick the 6.5x50SR. The average Japanese Army infantryman stood five-foot-three, or about the height of Natalie Portman. Japan used this rifle right up to when the Sino-Japanese War began in 1937, when they realized that, while the Chinese military had its problems, they had a better rifle than the Arisaka Type 38. China had a version of the German Mauser that fired a cartridge almost eight millimeters wide.
So, with that combat experience in mind, Japan went to work getting a better rifle. What emerged was the Arisaka Type 99. This fired a 7.7×58 cartridge, and Japan began producing them to get them to the front. Over 3.5 million Type 99s were made, but late in the war, the quality dropped, big time.
The Type 99 did put in an appearance during the Korean War. MilitaryFactory.com noted that these rifles were modified to fire the .30-06 round used by the M1 Garand. 133,000 of these rifles were pressed into service by South Korea. Not a bad swan song for a second-rate rifle.