Art of Japanese Spear Fighting
Naturally, there were many ryu and many sensei of bujutsu who specialized, often exclusively, in the use of the spear in combat. Famous among the former was the ancient Hozo-in ryu, named after the Hozo monastery where spear fighting was widely practiced. The Shinkage ryu, famed for its skillful swordsmen, also included spear fighting in its program of instruction. According to the literature of bujutsu, an expert spearman trained in any of these schools was studiously avoided not only by single warriors armed with the formidable katana but even by groups of warriors whom he could scatter with an intricate, yet impenetrable and deadly circular dance—his long weapon cutting, thrusting, slashing, and parrying as it cut through the air around him in a series of murderous whorls….
According to the major types of spears, there were two major arts or methods of using them: yarijutsu, the art of the straight spear, and naginatajutsu (or simply naginata), the art of the curved spear. Each art was practiced in accordance with innumerable styles, and there were subspecializations centered upon the use of all the various types of long and short spears and javelins. All shared a substantial number of basic techniques, such as the thrusts (tsuki), strikes (kiri), and parries which, in common with all cutting weapons, were also found in swordsmanship. Postures of readiness, introductory movements, styles of moving in toward an opponent or of sliding out of range of his blade, manners of reaching a target or of evading an attack, varied from school to school and even, within each, from expert to expert….
…In feudal times every part of the yari was used, including the bottom, which was usually capped with a pointed metal head; and that the position of readiness with the spear kept close to the side (in one of the predominant styles) was known as kai-kumi. We also know that several schools taught intricate patterns, high and low (jumonji-yari), in order to be able to strike not only from the front but also with characteristic sweeps directed at the opponent’s rear, while other schools specialized in parrying, hooking, and deflecting techniques known as kagi-yari. Naginatajutsu added to the techniques of the yari those circular cuts particularly appropriate to the curved shape of the naginata.
— Secrets of the Samurai, pp. 250-253