The Kama are Japanese and Chinese weapons that resemble the traditional farming sickle.
The sickle, implemented as a redesigned weapon form, was called a natagama and a large version is seen with the Grim Reeper. The kama is used to parry and cut an enemy from a distance before the final Kama strike was administered.
The forms today used in the martial arts classrooms have little or nothing to do with the original weapon and its historical techniques in battle. It is used with extreme skill to trap and parry even a sword yielding opponent. It is a lethal looking weapon that has no rival in instilling fear in an opponent and is made famous due to its apearance in many Ninja films.