Anbu

The, short for , are covert operatives of capable ninja that are dispatched by their village leader. There are apparently no true ranks within the Anbu; team leadership and hierarchy seem to be based on merit and experience. The leaders of the teams are called, a position held in high regard.

Overview
Because of the darkness involved in an Anbu's career, one's personality determines their eligibility into the force, leading to exceptional skilled shinobi whose personalities don't match the organisation to be rejected. As early as the Academy, accomplished children are scouted to eventually join. While recruiting, shinobi are hand picked by their village leader, for their individual capabilities and special skills. Age, background, gender, or previous rank bear no significance in this decision; however, in tradition, Konohagakure shinobi are not selected as Anbu unless they are at least 13 years old, with an 11-year-old Itachi Uchiha being a rare exception. Once joined, they undergo training including studying of the human body, and begin wearing masks to conceal their identity, leading to them using code names to identify each other.

Anbu nearly always make an appearance on important missions inside and in the vicinity of their village, but are mainly tasked with assassinations or disturbances in foreign countries. The assignments that they conduct to protect the village from exceptional threats include high-risk infiltration into enemy territory, dealing with extremely strong ninja, tracking, surveillance, interrogating enemy ninja to learn information and missions requiring specially trained ninja. Due to the actions of the group, one can appear changed and corrupted of kindness. Due to the often sensitive nature of their missions and the unique abilities they sometimes possess, Anbu are expected to destroy their bodies if they are too badly injured on a mission so that they can't be captured.

In Kirigakure, there is a special branch of Anbu known as hunter-nin: hunter-nin track down and kill missing-nin from Kiri, retrieving the head as proof and disposing of the rest of the body so as to not leave behind any information for their enemies. While Anbu are usually in squads and take orders from their captains, some elite Anbu have been handpicked by their Kage to serve directly under them. As such, any and all orders they receive come from their Kage and no one else. Anbu dislike letting anyone know their identities, and as such, most of Konoha's citizens aren't aware of who is and isn't an Anbu.

In Konoha, Anbu alongside the Konoha Military Police Force are the two forces that maintain peace. As such, there is no clear line what is the jurisdiction of the police, and what is the subject for investigation by the Anbu. At the discretion of the Hokage, the nature of the investigation would simply shift from one to the other, leading to the two factions clashing. Because Anbu are so vital to the village's operations, they cannot be arrested by the police without a warrant. Konoha formerly had a special branch of Anbu called Root, which acted like a secret police force that maintained public order from underground. Its members were trained to abandon all forms of emotion in order to follow Danzō Shimura's orders unquestioningly, even at the consequence of the rest of the village. Root members had a seal on their tongues that prevented members from speaking about their organisation.

After the Fourth Shinobi World War, in which the Five Great Shinobi Countries decided to fully unite themselves for the sake of peace, Kido Tsumiki believed that the stable peace would be inevitable for the Anbu to suffer a decrease in funding, as their services are no longer as vital. Kido had to orchestrate a few minor security incidents to ensure such funding will not be affected.

Uniform
Most Anbu wear some kind of mask to conceal their identities:
 * Konoha Anbu custom is to wear animal-styled porcelain masks, with some opting for more menacing-looking creatures.
 * Kiri Anbu wear masks with slits for eye-holes and the village's symbol etched into the forehead; these may or may not have patterns on them as well.
 * Sunagakure Anbu wear Suna flak jackets and masks shaped like inhuman faces.
 * A regiment of Anbu from the Land of Woods known as the Prajñā Group wear porcelain masks as well, modelled to resemble oni.
 * In the anime, Anbu from Hoshigakure are seen using masks similar to Konoha's.

They also have standard uniforms which, for Konoha Anbu, consist of black clothing, a grey flak jacket, metal arm guards and gloves, ninja sandals with spikes for travelling into mountainous regions, three ninja pouches on their back-waist and a signature spiral tattoo on their shoulder. Some Konoha Anbu wear black cloaks over their standard uniforms, and squad leaders may wear white cloaks. Most of them carry a sword, which is usually strapped to their backs.

Trivia

 * Stemming from the secrecy surrounding the group's membership, people speculate that villagers who come and go from the village without eating are Anbu.