Seven Ninja Swordsmen of the Mist

The was an organisation consisting of only the greatest blade-wielding shinobi of their generation that Kirigakure can produce. There can only be seven members at a time — hence the name. The swords of the Seven Swordsmen are passed down from generation to generation since the First Mizukage's era. They're considered mystical blades, and together, the Seven Swordsmen are capable of bringing down an entire nation, regarded as being the strongest shinobi in the village behind the Mizukage.

History
Some time after the Third Shinobi World War, the Seven Swordsmen of the time (Fuguki Suikazan, Jinin Akebino, Kushimaru Kuriarare, Raiga Kurosuki, Jūzō Biwa, and two others) cornered a Konoha team. The team was rescued by Might Duy, who fought all seven using the Eight Gates Released Formation. In the manga, it is only known that Fuguki survived, while in the anime, only Jūzō and Raiga survived along with him.

The group's make-up changed over the following years: Mangetsu Hōzuki joined and mastered all seven swords, and Fuguki was killed and replaced by his subordinate, Kisame Hoshigaki. The group's remaining members started dying — as in the case of Mangetsu — or becoming missing-nin and taking their swords with them — as in the cases of Kisame and Zabuza Momochi, as well as Jūzō and Raiga in the anime. By the time of the Fourth Shinobi World War, only Hiramekarei wielded by Chōjūrō remained in Kirigakure's possession.

The "strongest" generation of the Seven Swordsmen was later reincarnated to fight for Akatsuki during the Fourth Shinobi World War. Five of the swordsmen were reunited with their former swords, which they used in battle against the Third Division of the Allied Shinobi Forces. Although the Third Division suffered numerous casualties, they were able to seal all of the Seven Swordsmen by the second day of the war. With the release of the Impure World Reincarnation, the sealed swordsmen's souls were ultimately returned to the Pure Land.

In the anime, the remaining six swords returned to Kiri's possession, including Kubikiribōchō from Kakashi Hatake, Samehada taken by Killer B, and Kiba that was in the possession of Omoi. As such, the unit had been reinstated, with Chōjūrō personally choosing Kagura Karatachi to replace his position. Shizuma Hoshigaki later forms his own version of the group called the New Seven Ninja Swordsmen, comprised of malcontents who wish to return the village to its roots as the "Village of Bloody Mist". Recruiting Kagura to their cause, they take advantage of his access to the armoury where the seven blades are stored and steal them with plans of staging out a coup d'etat. However, they failed to start their revolution due to the actions of Boruto Uzumaki, his friends, Chōjūrō and eventually Kagura himself, which resulted in them being defeated and taken into custody.

Swords

 * A bandaged double-handled sword that is capable of storing and emitting the user's chakra which can then take on various forms. It is also called a.
 * A sword consisting of a single-sided axe and a hammer joined by a length of chain. Said to be capable of crushing any and all defences. It is also called a.
 * Twin swords that are imbued with lightning which increases their cutting power. They are said to be the sharpest swords ever forged. They are also called.
 * A giant sword with a butcher-knife-like appearance, the wielder can use the semi-circle on the blade to decapitate an opponent's head, hence the name. The sword has an ability to regenerate using the iron absorbed from the blood of those it cuts down. It is also called a.
 * A sword in the shape of a needle with a long thin wire that resembles thread attached to it, which can be used to pierce enemies and "sew" them together in human bundles. It is also called a.
 * The most terrifying of the seven blades, it has the appearance of a giant knife covered in shark scales. It is a sentient, living weapon and has the ability to "eat" chakra. It is also called a.
 * A sword that has a scroll full of explosive tags incorporated into it, lined up behind the blade, combining swordsmanship and explosions. It is also called a.

Other Members
An earlier generation of the organisation consisted of Fuguki, Jinin, Jūzō, Raiga, Kushimaru and two other unidentified shinobi:
 * Hiramekarei's wielder: A shorter individual with moused-up hair who wore his forehead protector as a choker and a utility belt around his waist along with a flak jacket and a pinstriped shirt and pants. He carried the Twinsword strapped to his back horizontally.
 * Shibuki's wielder: A slender man who wore a pinstriped shirt and a cloth-mask that only showed his eyes.

Trivia

 * It seems to be a tradition for the members and aspiring members of the Seven Swordsmen to have sharpened teeth, the only exception being Raiga in the anime.
 * When the group debuted in the anime, at least two of the sword designs differed to later appearances in the anime and in the manga.
 * All named members of the Seven Swordsmen have surnames, or a given name in the case of Chōjūrō, derived from a type of produce. This does not hold true for Raiga.
 * All of the reincarnated swordsmen have bandages around their necks.
 * At least two (four in the anime) of the members became missing-nin, while one was discovered to be a traitor, leaking confidential information to other villages.
 * Although Mangetsu was said to have mastered use of all the swords, other members of his generation wielded six of them, leaving Hiramekarei as the blade he likely primarily used.
 * At least two (one in the manga) members of the Seven Swordsmen were former Anbu members.
 * At least two (three in the anime) members of the Seven Swordsmen managed to fake their own deaths or regain life later on by means of an accomplice.
 * In the anime, Kushimaru and Jinpachi were known collectively as the due to their many acts of cruelty in their lifetimes.
 * Due to the tradition of the group, every single Kiri villager strives to master kenjutsu from their childhood on wards.