Kunai

A kunai (苦無, kunai?) is a Japanese tool possibly derived from the masonry trowel. Two variations are the short kunai (小苦無, shō-kunai?) and the big kunai (大苦無, dai-kunai?). It is a good example of a very basic tool which, in the hands of a martial arts expert, could be used as a multi-functional weapon. It is commonly associated with the ninja, who used it to gouge holes in walls.