is a common kobudo tool taught in most Okinawa Shorin-Ryu karate schools, as a close, combat weapon. The are is known as sai-jutsu. Sai are held by a handle (tsuka) to extend the reach of the weapon as well as to enable the defender to thrust the point (saki) into the opponent. But, it also is held in reverse grip for blocking and punching. One or two additional sai are often placed in one's belt (obi) for throwing, and indeed, most sai kata (forms) show technique (waza) for throwing sai. When, training in a dojo, a target board is placed on the dojo floor for practice. If one trains outside, the ground is used as a target to train karate-ka to place sai in an opponents foot. Likewise, a human-shaped target can be placed nearby for throwing sai at a torso.
The distinct, 3-pronged trident, has a pointed shaft surrounded by two curved prongs (yoku) and may have originally have been used by Okinawan farmers similar to a pitchfork, seed-furrowing tool, or even used bo Okinawan fishermen as a harpoon-like tool known as nuntei-bo. Since iron was uncommonly smelted on Okinawa prior to the 19th century, it is likely the weapon was imported from China by a member of the Okinawan royal family or bodyguard. It is also possible that the sai originated by breaking the trident off nuntei-bo.
The sai, like many other Okinawa weapons, has many different kata (forms) as well as many bunkai (self-defense applications). When you sign up for classes at your local Okinawan karate dojo, be sure to find out if your sensei (teacher) is certified to teach sai, and also find out if they charge additional fees for kobudo.