There is an un-verified but plausible legend that the origin of the sai came from the Okinawa. Kanagushi Ufuchiku ( 1841-1926) an Okinawan police captain who was a known expert of sai-jutsu.

Originally, the sai was made out of two seperate parts: the stem and the curved prongs. These two parts were then pounded together in a process similar to that used by swordsmiths. Around late 19th century, another method was used. A finished sai would serve to create a sai-shaped cavity in the ground. Molten iron was poured into this shape, producing a perfect twin of the first sai when the iron had hardened. Rough edges were removed and afterwards the sai was polished.

 

The stem of the sai should cover the complete forearm, to guarantee full protection when countering an attack. The butt of the handle can have various shapes and can be used in the same way as a bullet. Another vesion of the sai, called jutte or jitte was a weapon used by the Japanese Police. It is smaller than the sai, and has only one prong.