Kunai

, like shuriken, are one of the most common tools used by shinobi. It is a black dagger — about the length of one's hand — with a handle wrapped in bandages and a circular end. While usually kept in a shinobi's weapon pouch, they can also be kept on spring-loaded wires up the user's sleeve.

Kunai generally are designed for thrusting and stabbing, but can be thrown as a projectile as well. Using it as ranged weapon, shinobi can attach an explosive tag to the blade, causing it to detonate when it reaches near its target. This use of the weapon is known as an. Kunai can also be empowered with chakra, allowing it to be capable of cutting through solid wood and stone.

Types of Kunai
Different types of kunai have been seen in the series:
 * Zabuza Momochi was shown using a special kunai that curved inward on one side, making it more suitable for stabbing and thrusting. This type is also shown used by Kirigakure in the anime.
 * Kabuto Yakushi, when threatening to kill a hospitalised Sasuke Uchiha in Part I, held a kunai with a curved blade to Sasuke's neck. This seems to be the same type that Rōshi used. Its design is reminiscent of a Chilean Corvo knife.
 * Before the first part of the Chūnin Exams, Zaku Abumi used kunai with holes in the middle and no rings at the ends.
 * The kunai that Kotetsu Hagane threw at Sukima during the first part of the Chūnin Exams had a tassel connected to the ring (possibly to make it more noticeable).
 * During the second part of the Chūnin Exams, Team Oboro used double-bladed kunai while facing Team 7.
 * Minato Namikaze used three-bladed kunai that had a special seal applied to them in order to perform his Flying Thunder God Technique.
 * When the Third Division engaged the Seven Ninja Swordsmen of the Mist, three-pronged kunai were shown.
 * In the anime, a member of the Kurama clan used a kunai with a shape similar to a combat knife.
 * Tenten used a smaller version of kunai when threatening Menma.
 * During the Chūnin Exam, Tenten used two kunai with curved blades, which were connected through a short chain in the bottom ring.
 * Shiin used kunai with long, thin, red ropes attached to them, similar to a Jōhyō.
 * The Father puppet, created by Sasori, was equipped with a segmented wooden whip covered with kunai.
 * Deidara was shown wielding a kunai with a square hilt in his mouth. Asuma was also seen with a pair of these after being reincarnated.
 * During their battle with Hidan, Izumo Kamizuki and Kotetsu used kunai the size of ordinary blades to attack him. When next observed, the pair were connected by a length of chain, with a weight attached to its centre.
 * In the manga, the Prajñā Group used very long kunai to assault Danzō Shimura. However, in the anime, these were replaced instead by the standard variant of kunai and later katana.
 * An unnamed Iwa shinobi of the First Division used a kunai with a manriki-gusari attached to its hilt, in a similar manner to a kusarigama, during their initial engagement with the Akatsuki forces in the Fourth Shinobi World War.
 * An unnamed Kiri shinobi of the Fourth Division used a kunai with a noticeably serrated edge along at least one of its sides during their first direct engagement with the Second Mizukage and Third Raikage in the Fourth Shinobi World War.
 * Obito Uchiha owns several kunai of immense size, storing them in the other dimension to launch them with Kamui in quick succession.
 * In the anime, a young Naruto finds a special Takigakure kunai with an extending blade on one side before being pursued by The Taki Kunoichi. It had two thin blades, one larger and one smaller, causing it to resemble a jutte or a hachiwara.
 * Among the many weapons created by Iō there were two variations of a kunai: a double-bladed one without a handle, but with poison on the blade (and therefore, dangerous to the user), and one with another ring at the end instead of a blade. Obviously, they were basically useless.
 * Shinobi from Benisu Island uses kunai with curved sides and flat surfaces.
 * In the anime, Indra Ōtsutsuki used kunai carved out of stone.
 * Kusuna used a double-bladed kunai that could disconnect into two kunai during his first attempt to assassinate Shion. The kunai each had a grip around the handle.
 * During the assassination attempt on Shion's life, Shizuku was seen using a kunai with two retractable blades at the hilt, which in turn was attached to a chain ending in a handle, thus allowing the kunai to be wielded similarly to a Jōhyō.
 * In his battle with Neji, Kidōmaru formed kunai using his Spider Sticky Gold technique.
 * In the light novel adaption of Naruto: Mission: Protect The Waterfall Village! (novel), Hisame was able to use a kunai made of water.
 * In the OVA Mission: Protect the Waterfall Village!, Murasame and a group of nine unnamed Amegakure shinobi used a variety of kunai to attack Naruto's group.

Kunai Launching Weapons

 * Kiba Inuzuka employed the use of a clone of Akamaru to release kunai when approached. The doppelgänger swelled and then burst, launching the kunai at the opponent.
 * Tenten's metal sphere had kunai welded into it, which when detonated, sent shrapnel fragments flying in an omnidirectional manner.
 * Chiyo used a simple length of cord to thread numerous kunai together, in such a manner that the entirety could be released and thrown consecutively with just a single motion. A similar arrangement was employed by a shinobi of the Third Division, during their attack on the Seven Ninja Swordsmen of the Mist, in the Fourth Shinobi World War.
 * Dotō Kazahana's army of Yukigakure ninja used mortars mounted on their train compartments to launch massive amounts of kunai at a very rapid rate.
 * The ninja of the Land of the Sky equipped themselves with Handheld Kunai Launchers that could fire kunai rapidly, similar to machine guns.
 * The ninja of the Land of the Sky set up crossbows that launch kunai as traps in Amaru's village after attacking it.
 * When Hiruko declared war against the Five Great Shinobi Countries and Konohagakure was blamed for it, Tsunade had prepared a large amount of mortars with giant kunai loaded into it, akin to missile launchers, in an attempt to defend her village from Sunagakure's attack.
 * In the anime, kunai launching cannons were used as part of a trap, firing automatically at intruders.

Trivia

 * Historically, in reality, the kunai were just simple farming tools. When the Japanese emperor announced Martial Law and banned weapons, farming tools were among the easily disguised substitutes adopted, mostly because of how cheap they were to manufacture.