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For "kunai grass", see Imperata cylindrica.

A kunai ( kunai?) is a Japanese tool possibly derived from the masonry trowel.[1] 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 basic tool which, in the hands of a martial arts expert, could be used as a multi-functional weapon.[2] It is commonly associated with the ninja, who used it to gouge holes in walls.[1]


The kunai was conventionally wrought in ranges from 20 cm to 60 cm, with the average at 40 cm. The kunai was used by peasants as multi-purpose gardening tools and by workers of stone and masonry. The kunai is not a knife, but something more akin to a crowbar. The blade was soft iron and unsharpened because the edges were used to smash plaster and wood, to dig holes and to pry. Normally only the tip would have been sharpened. The uses a kunai was put to would have destroyed any heat-treated and sharpened tool like a knife.

Kunai normally had a leaf-shaped blade and a handle with a ring on the pommel for attaching a rope. This would allow the kunai's handle to be wrapped to act as a grip or, when used as a weapon, to be strapped to a stick as an expedient spear; to be tied to the body for concealment; or to use as an anchor or piton. Contrary to popular belief, they were not designed to be used primarily as throwing weapons, though they could be thrown to cause damage. Instead, they are a thrusting and stabbing implement.


Many ninja developed weapons that were adapted farming tools, not unlike those used by Shaolin monks in China. Since kunai were cheaply-produced farming tools of a decent size and weight and could be easily sharpened, they were readily available to be converted into simple weapons.

As a weapon, it is larger and heavier than a shuriken and with the grip could also be used in hand to hand combat more readily than a shuriken. In addition, it could be used for climbing, either as a kind of grappling hook or as a piton.[2]

There are several varieties of kunai, including short kunai, long kunai, narrow bladed types, saw-toothed types and wide-bladed types. In some cases, the kunai and the shikoro, a wide-bladed saw with a dagger-type handle, are hard if not impossible to distinguish. The kunai blade can be used to gouge holes in a door to take out doorknobs.

Popular culture[edit]

A highly stylized kunai, as often portrayed in popular culture

As with the ninjutsu, the exaggeration persistent in ninja myths played a large role in creating the current popular culture image of kunai. In the mythology of ninja, the kunai is commonly portrayed to be a Japanese knife that is used for throwing as well as stabbing. The kunai often appears in manga/anime and video games as a weapon for ninjas (either primary or back-up).

See also[edit]