The Seven Ninja Swordsmen of the Mist (霧の忍刀七人衆, Kiri no Shinobigatana Nananin Shū) is an organization 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. Four members are currently known, although the third, Raiga, only appeared in the anime. Three of them are missing-nin.
The members of the Seven Ninja Swordsmen were the people who came from the Bloody Mist's graduation exams with the greatest battle skills. However, the members also had a great lust for power. This led many of them to defect and become missing-nin. Kisame Hoshigaki was the first to abandon Kiri, and joined Akatsuki. Zabuza Momochi would later do the same after a failed coup d'etat and assassination attempt on the Mizukage. Before leaving, he encountered a boy named Haku with a unique ice kekkei genkai and took the boy with him, as well as the Demon Brothers, Gōzu and Meizu. It hasn't been confirmed when Raiga Kurosuki left Kiri, but it was around the same time when he discovered a boy named Ranmaru, who ended up having a similar relationship with Raiga to that of Zabuza and Haku. Ranmaru also had a special dōjutsu which Raiga used for his own purposes, furthering their relationship to that of Haku and Zabuza's.
The Hozuki brothers, Mangetsu and Suigetsu, both trained with the intention of joining the Seven Ninja Swordsmen together. However, their ambitions were cut short when Mangetsu died and Suigetsu was captured by Orochimaru. Suigetsu has since taken an interest in collecting all of the swords of the Seven Swordsmen for himself.
According to Suigetsu, the swords of the Seven Swordsmen are passed down from generation to generation.
Known swords Kubikiri Hōchō (首斬り包丁; English "Executioner's Blade"; Literally meaning "Decapitating Carving Knife"): A giant knife with a butcher-knife-like appearance, the wielder can use the hole on the blade to grab an opponent's head and decapitate them, hence the name. It has a detachable handle to make it easier to carry around. It was formerly owned by Zabuza, and was later retrieved by Suigetsu. It was damaged by Killer Bee, and snapped in half by the Fourth Raikage.
Samehada (鮫肌; Literally meaning "Shark Skin"): The most terrifying of the seven blades, it has the appearance of a giant knife covered in shark scales. It also has the ability to "eat" chakra. Unlike other swords, it doesn't cut, but actually shaves ribbons of flesh off of foes just like shark's skin, another courtesy of the name. When fully revealed, the blade shows to have a chakra absorbing mouth at the end of it. Kisame can also absorb Samehada within his body turning him into a shark-like mutant creature. Spikes jut out of the handle when anyone other than the rightful owner tries to pick it up. It is currently owned by Kisame but seems to have taken a liking to Killer Bee.
Hiramekarei (ヒラメカレイ): A bandaged double-handled sword that is capable of creating a chakra layer around itself in the form of a hammer. It is unknown if it is capable of forming other weapon types. It is currently owned by Chōjūrō.
Rai Rōga (雷竜牙, Anime only; Literally meaning "Lightning Fangs"): Twin pikes which resemble dragon fangs. The wielder can use the pikes to channel lightning release techniques. They can also conduct lightning as well. They were formerly owned by Raiga, and are currently at the bottom of a river in the Land of Rivers after Raiga killed himself.