Many keep their karate training deliberate on a route of not diluting the stduy of empty handed fighting with kobudo (weapons) training. Not surprising given that Karate-Do means the Way of the Empty Hand. However, certain styles of many martial arts train it alongside their open handed fighting. It is often a hot debate in regards to "if" or "when" a student should begin the practice of kobudo if karate is their true aim.

The most notable of the weapons typically practiced alongside the Japanese martial arts are the Katana (Samurai Sword), Bo (long staff), Jo (Short staff), Nitanbo (two short sticks), Sai (3 pronged knife like weapon), Tonfa and the Nunchaku. Sai is often a popular choice and it is a weapon that has attributes of word and knife but also has other form and functions which make it somewhat unique.

The history of sai not really known and there is a lot of speculation. Sai does not have a unique origin in Okinawa. Variants exist in other Asian countries and like karate it may well have been influenced by imported knowledge from other Asian regions.

However, many of the kobudo weapons , regardless of region of origin, are often argued to be farming/fishing tools and therefore one theory is that the sai stemmed from a farming tool e.g. it could have been a tool used to create holes in the ground for planting or as a small pitch fork for picking up hay. However, some believe it was designed as a weapon from the beginning given its size and also the cost of metal when one could find other materials (e.g. wood) to do such simple farming tasks.

Another possibility is that it was derived from the Buddhist symbol seen on shrine roofs, which is the religious symbol known as the manji (a symbol that many people comment on in relation to its similarity to the NAZI swastika, however the root source of the Buddhist symbol and its intent could not be more different).

Sai are made of metal however modern training versions exist in aluminum and plastic which provide beginners a lighter and safer experience in the ir early days of handling the weapon. The size varies and depends on the length of an individuals forearm. The shaft should cover the forearm and extend past by around 1.5 inches to provide full length forearm protection and an extending point to allow a kisaki impact if an elbow leading strike is used as the a technique.

A well crafted sai is said to have a balance point just above the moto. Our diagram above labels the tsuka as the handle of the sai which is normally wrapped in a grip but it should be noted that the pommel (or thick and often rounded tip) is termed the tsukagashira.