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For the grass, see Imperata cylindrica.
A highly stylized kunai, as often portrayed in popular culture

A kunai ( kunai?) is a Japanese tool possibly derived from the masonry trowel.[1] There are two widely accepted variations of the kunai: the 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multi-functional weapon.[2] It is commony associated with the ninja, who used it to gouge holes in walls.[1] Kunai were originally made to be farming tools but soon evolved into the devious weaponry they have become today. Many popular manga and ninjutsu characters use kunai as both their primary and secondary weapons.


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 a multi-purpose gardening tool and by workers of stone and masonry. The kunai is not a knife, but something more akin to a crowbar. The blade is made of soft iron, and is left unsharpened because the edges are used to smash (plaster and wood), dig holes, and pry. Normally, only the tip is sharpened.

Kunai normally had a leaf-shaped blade and a handle with a ring on the pommel for attaching a rope. This allows the kunai's handle to be wrapped to function as a grip, or to be strapped to a stick as a makeshift spear; to be tied to the body for concealment; or to be used 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 were primarily non-weapon tools and, when used as weapons, were stabbing and thrusting implements.


Many ninja developed weapons 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 depiction[edit]

As with 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 and anime and video games as a weapon for ninjas (either primary or back-up). This is most attributed to the very acclaimed anime and manga series, Naruto. It is also used by the Mortal Kombat character, Scorpion.

See also[edit]