Kunai

Kunai Knives
A Kunai Knife was a black dagger about the length of (as a general unit) Naruto's hand. It was a common ninja tool (either used as a melee weapon or thrown) and most of the characters in the series frequently use it, with the exception of individuals such as Rock Lee or Kimimaro. Many ninja cleverly attack by attatching a paper bomb (a short length of paper that, when burnt, detonates) to the blade. The kunai is commonly thrown so that it lodges in an object near the target, and then the explosion from the paper bomb destroys it (the target). Kunai knives and shurikan are the two most common ninja tools in the world of Naruto.