is the term for a traditionally-made in the form of a spear, or more specifically, the straight-headed spear. The martial art of wielding the is called .
The forerunner of the is thought to be the , a lance derived from the qiang (Chinese spear). These are thought to be from the Nara period (710âÂÂ794). Another polearm, the naginata (glaive), became important in the late Heian.
The term appeared for the first time in written sources in 1334, but this type of spear did not become popular until the late 15th century. The original warfare of the was not a thing for commoners; it was a ritualized combat usually between two warriors, who would challenge each other via mounted archery. In the late Heian, battles on foot began to increase, and , a bladed polearm, became a main weapon along with the yumi (Japanese longbow).
The attempted Mongol invasions of Japan in 1274 and 1281 provoked a shift in weaponry and in warfare. The Mongols employed Chinese and Korean footmen wielding long pikes and fought in tight formations. They moved in large units to stave off cavalry. Polearms were of much greater military use than swords due to their significantly longer reach, lighter weight per unit length (though overall a polearm would be hefty), and excellent piercing ability.
In the Nanboku-chà  period, battles on foot by groups became the mainstream, and the appeared. However, were not yet the main weapon. However, after the decade-long à Ânin War (1467-77) in the Muromachi period, large-scale group battles started, employing (peasant foot troops), who fought on foot and in close quarters, and the yari, yumi, and, after 1543, the (Japanese matchlock) quickly became the most utilised weapons.
This shift made the and traditional (sabre) styles obsolete on the battlefield. These were often replaced with the tachi known as the (long-handled sword) and the short, lightweight .
Around the latter half of the 16th century, wielding pikes () with a length of became the main forces in armies. They formed lines with soldiers bearing and short spears. Pikemen formed a two- or three-row line and were trained to move their pikes in unison under command.
Not only but also samurai fought on the battlefield, using the yari as one of their main weapons. For example, Honda Tadakatsu was famous as a master of one of the Three Great Spears of Japan, the . One of the Three Great Spears of Japan, the ) was treasured as a gift, and its ownership changed to Emperor à Âgimachi, then the Shoguns Ashikaga Yoshiaki, Oda Nobunaga, Toyotomi Hideyoshi, Fukushima Masanori, and so on, and has been handed down to the present day.
In the Edo period, the fell into disuse. Greater emphasis was placed on small-scale, close-quarters combat, so the convenience of swords led to their dominance, and polearms and archery lost their practical value. During the peaceful Edo, were still produced (sometimes by renowned swordsmiths), although they were primarily used as ceremonial or police weapons.
were characterized by a straight blade that could be anywhere from several centimeters to or more in length. The blades were made of the same steel () from which traditional Japanese swords and arrowheads were forged, and were very durable. Throughout history many variations of the straight blade were produced, often with protrusions on a central blade. blades often had an extremely long tang (; ä¸Âå¿Â); typically it would be longer than the sharpened portion of the blade. The tang protruded into a reinforced hollow portion of the handle ( or ) resulting in a very stiff shaft making it nearly impossible for the blade to fall or break off.
The shaft ( or ) came in many different lengths, widths, and shapes; made of hardwood and covered in lacquered bamboo strips, these came in oval, round, or polygonal cross section. These in turn were often wrapped in metal rings or wire (), and affixed with a metal pommel (; ç³çªÂ) on the butt end. shafts were often decorated with inlays of metal or semiprecious materials such as brass pins, lacquer, or flakes of pearl. A sheath (; éÂÂ) was also part of a complete .
Various types of points or blades existed. The most common blade was a straight, flat design that resembles a straight-bladed double edged dagger. This type of blade could cut as well as stab and was sharpened like a razor edge. Though is a catchall term, the simple () or straight spear is distinguished from the , which can have additional horizontal blades. can also be distinguished by the types of blade cross-section: the triangular sections were called and the diamond sections were called .
A shaft can range in length from , with some in excess of 6 metres.