The samurai sword, sometimes called a katana, is a slightly curved Japanese sword. The single-edged blade is always longer than 23 inches and has a grip long enough to accommodate two-handed use. The sword is most commonly associated with the samurai, though today, collectors, martial arts practioners and reenactors commonly own and use the swords.

Samurai swords were created during the Muromachi Period of feudal Japan, which lasted from 1392 to 1573. The primary innovation that was applied to these swords when they were initially designed was to store it with the blade facing outward so that it can be drawn as well as cut an opponent in one motion. Between the 14th and 15th centuries, they were approximately 73 cm long, but this fell to 60 cm during the 16th century, and were switched back to 73 cm as the century drew to a close. The blades are comprised of both high carbon and low carbon steel fused together. This is because high carbon steel is hard but brittle, while low carbon steel is malleable, though easily dulled. Thus, the outer casing of the blade is made from low carbon steel, while the edge is made from high carbon steel, resulting in a highly effective, deadly blade.

After inspecting the damaged swords, Amakuni and his son realized the problem had been caused by bad forging and vowed to create the perfect sword. They spent days praying to the Gods and after a week, the image of the Japanese katana came to them in a dream. Believing the sword to be divinely inspired, Amakuni presented it to the emporer to use in battle. The next time they returned home, not a single sword had been damaged or broken. The period from approximately 1200 through the end of the fifteenth century are commonly considered the golden age of the Japanese katana. These periods were called the Kamakura, which lasted until about the mid-1300s and the Muromachi, which continued from about 1337 until 1573. The swords popularity was a result of the Mongol invasion of the country. The Japanese realized the importance of a strong national army and sword smiths went to work forging a weapon that would be appropriate for this national defense.

The golden age of the Japanese katana was follwed by a dark age period in which many of the skills of sword-making were lost. The swords were being produced too quickly for them to feature the same quality that was possible during the golden ages. Many sword smiths also turned their attention to making guns around the mid 1500s, further lessening the skills of sword makers because they were out of practice. Following the unification of the country by the Shogun Hideyoshi, the peasants were disarmed and only samurais carried swords. The country was at peace for four centuries and sword making was elevated to a fine art. The swords made during this period were known as Shinto, which meant new sword in Japanese. They were decorative in nature and were rarely, if ever, used in battle.

The modern age of the Japanese katana began after World War II. Sword smiths inside of the country, as well as around the world, attempted to recreate the forging techniques used during the height of the golden age of Japanese katana. Some makers have furthered the development of the sword by creating a virtually indestructible version of the Japanese katana.