The kunai (苦無) is a Japanese tool possibly derived from the masonry trowel. There are two widely recognized variations of the kunai are short kunai (小苦無 shō-kunai) and the big kunai (大苦無 dai-kunai). The short kunai is sometimes mistaken as a throwing shuriken. This basic hand tool became a multi-functioning weapon in the hands of a martial arts master. The kunai is commonly associated with the ninja, and you will also see this weapon used in Japanese manga.