The kama(鎌 or かま?) (sometimes referred to as the kai or double kai. Kama made with intentionally dull blades for kata demonstration purposes are referred to as kata kai) is a traditional Filipino and Japanese farming implement similar to a sickle used for reaping crops and also employed as a weapon. The kama is often included in weapon training segments of karate, silat and in some Chinese martial arts.
Before being improvised as a weapon, the kama was widely used throughout Asia to cut crops, mostly rice. It is found in many shapes and forms in Southeast Asia and is particularly common in martial arts from Indonesia and the Philippines. It is also used in Chinese martial arts but not often. From one or both of these areas, the kama was brought to Okinawa and incorporated into the martial art of te (hand) and later karate (empty hand).
The kama can be used singly or in pairs. Both the point and sharpened edge of the metal blade are called into use, Okinawan kata suggesting that it could also be used to block, trap and disarm an opponent's weapon. The point at which the blade and handle join in the "weapon" model normally has a nook with which a staff can be trapped. The edge of a traditional rice sickle, such as one would purchase from a Japanese hardware store, continues to the handle without a notch, as this is unneeded for its intended use. The hard edge of the blade would be kept razor-sharp to enable efficient cutting of crops, though this is sometimes a cause of training accidents by unskilled wielders, for whom blunt training versions of the weapon are created. This weapon not only is very sharp and can inflict damage, but is also said to hold a fear factor against the opponent.
The kama is a popular weapon for kata competitions but modern forms competitors often simply adapt their empty hand routine while holding kama with little actual kama technique, or employ elaborate weapon-juggling routines that differ radically from the focused Okinawan forms.
The kama is used today for martial arts. There are only two registered forms in Japan in modern day. They are called Kanigawa and Tozan. The forms today in martial arts classrooms have little or nothing to do with the techniques used in past battle forms.