This site contains information about the various Japanese weapons used since 1543, when guns first were brought to Japan, until 1945 when Japan gave up all weapons development at the end of the Pacific War.
Europeans brought guns to Japan in the middle of the Warring States Period. Guns quickly were adopted by many of the feudal lords and by religious groups who were in conflict. It was reported by one of the Christian missionaries of the period that after ten years time, that is in 1553, there were more than one hundred thousand guns in Japan. Perhaps, by 1600, the year of the battle of Sekigahara which ended the Warring Period, Japan was the biggest gun country in the world. About three hundred thousand guns were supposed be there at that time. The guns used in this period were matchlocks, the so-called Tanegashima, after the name of the small island off the southern tip of Kyushu where guns first were introduced to Japan.
After the battle of Sekigahara until the mid-nineteenth century Japan was a closed country which kept very limited relations with other countries; Japan had no domestic wars for almost two and a half centuries. There was no need for guns and no gun development was made.
After 1868 and during the Restoration Period of the Emperor Meiji, Japan became very keen to develop her own weapons, and she did do for just three-quarters of a century, until 1945. In 1880 Japan adopted the Model 13 Murata rifle, the first modern rifle to appear in Japan since the ages of the Tanegashima. (Actually she imported various European and American rifles during the period of 1855 to 1868 and it total number reached about seven hundred thousand.)
Japan was very fast in catching up to the Western countries in weapon development.
Early in the twentieth century Japan's weapon development nearly was equal to that of the Western nations. Japan tested her weapons in battle with Russia in 1904-1905, and she used machine guns on a large scale. Japan developed a new infantry rifle in 1905 and she improved upon the design of a heavy machine gun she had purchased from France and manufactured under license; both of these new weapons were called Model 38, having been developed in the 38th year of the reign of the Emperor Meiji.