The earliest discovered spears in Japan are called hoko yari. They are recognizably modeled after chinese spears, and feature a hollow slot which differs from a more traditional japanese yari spear which usually feature an elongated nakago, i.e. spine. The spine was attached to a hollowed out shaft with pegs, that were placed through holes in the spine, similarly to japanese swords are attached to the tsuka or handle. As a term, yari became more common only from 14th century onwards, and only after the Oni-wars during the Muromachi-period (1467-1477) did the use of spears become more common as the ashigaru, common footsoldiers, became more commonplace. Before the Muromachi-period, bushi-warriors specializing in the use of the spear did exist, but the naginata was a more popular weapon of choice at the time. Japanese spears were almost uniquely melee weapons and were not used for throwing purposes. There exist several different lengths of the yari and the shape of the blade could change considerably. During the halfway point of the 16th century long nagae yari became more common, measuring typically around 4,5 to 6 meters in length and meant primarily for formation-based warfare. The blades of the yari were made of tamahagane, the same type of steel that swords were made in ancient Japan. Different blade designs included among others the straight-bladed su yari (choku-sō) and the sideways-blade furnished kama yari. There are also variations in the cross-section of the spear blade, such as the triangular sankaku yari and the diamond-shaped ryō-shinogi yari. The length of the shaft of the yari, called the nagaye or ebu could differ greatly between one and six meters. The shaft was typically made of hardwood which was coated with lacquered bamboo strips. The shape of the shaft also changed, having a cross-section of an oval or a polygon. The shaft was often reinforced with metallic bands, dogane. The spear was often equipped with a pommel, ishizuki which functioned as a counterweight to the spear blade. The pommel could be shaped like a ball of a spike, for example.

The spear techniques used in Bujinkan chiefly originate from Kukishinden Ryu, but for example Kumogakure Ryu also makes used of the kama yari. Though yari is in chiefly a thrusting weapon, the entire yari is used in spear techniques of Bujinkan.