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