Tailed Beasts (Rukard)

The tailed beasts (尾獣, bijū) are nine giant demons that serve to drive the plot of the Naruto series. They are differentiated by the number of tails they have, with each possessing an amount from one to nine. The tailed beasts are large, living forms of chakra, sometimes referred to as "Chakra Monsters" (チャクラのバケモノ, Chakura no Bakemono), giving them power that far outmatches most shinobi. However, this immense strength is tempered due to their bestial nature, which restricts them from being intelligent enough to use it effectively. When the tailed beasts are sealed within humans, they are able to benefit from the knowledge of their hosts, giving them the ability to speak and better utilize their powers.

History
In the beginning of ninja history, centuries before the founding of the ninja villages, there existed a god-like entity known as the Ten-Tails, which plagued the world until the Sage of the Six Paths defeated and sealed the beast within himself, making him the first jinchūriki. However, knowing that his death would release the Ten-Tails back into the world, the Sage used his ability, the "Creation of All Things", to divide its chakra into the nine tailed beasts, before using Chibaku Tensei to seal its body in what would become the moon. Some time after being created, the Sage gave each of the young tailed beasts a name and told them that they would always be together, even when separated. He also told them that one day, they would become one entity again with a different name as well as forms than they did at that time; when the time came for them to understand what true power was. Despite their close relation to one another, there is a significant amount of friction between them. One such cause was due to Kurama's belief that their strength was determined by their number of tails.

Shukaku
Shukaku (守鶴, Shukaku), more commonly known as the One-Tail (一尾, Ichibi), is a tailed beast that was last sealed within Gaara of Sunagakure. It has been captured by Deidara, then extracted and sealed by Akatsuki. It currently does not have any host.

Matatabi
Matatabi (又旅, Matatabi), more commonly known as the Two-Tails (ニ尾, Nibi), is a tailed beast that was sealed within Yugito Nii of Kumogakure. It has been captured by Hidan and Kakuzu, then extracted and sealed by Akatsuki. It was later resealed into a reincarnated Yugito during the Fourth Shinobi World War. It currently does not have any host.

Isobu
Isobu (磯撫, Isobu), more commonly known as the Three-Tails (三尾, Sanbi), is a tailed beast that was formerly sealed in Yagura of Kirigakure. It has been captured by Deidara and Tobi, then sealed by Akatsuki. It was later resealed into a reincarnated Yagura during the Fourth Shinobi World War. It is now sealed within Kazumi.

Son Gokū
Son Gokū (孫悟空, Son Gokū), more commonly known as the Four-Tails (四尾, Yonbi), is a tailed beast sealed within Rōshi of Iwagakure. It was captured by Kisame Hoshigaki, then extracted and sealed by Akatsuki. Son was later resealed into a reincarnated Rōshi during the Fourth Shinobi World War. It currently does not have any host.

Kokuō
Kokuō (穆王, Kokuō), more commonly known as the Five-Tails (五尾, Gobi), is a tailed beast sealed within Han from Iwagakure. It has been captured, extracted, and sealed by Akatsuki. In the anime, Kokuō is indicated to have been one of the two tailed beasts that Akatsuki captured before the start of Part II. It was later resealed into a reincarnated Han during the Fourth Shinobi World War. It currently does not have any host.

Saiken
Saiken (犀犬, Saiken), more commonly known as the Six-Tails (六尾, Rokubi), is a tailed beast sealed within Utakata of Kirigakure. It has been captured by Nagato in the anime, then extracted and sealed by Akatsuki. It was later resealed into a reincarnated Utakata during the Fourth Shinobi World War. It currently does not have any host.

Chōmei
Chōmei (重明, Chōmei), more commonly known as the Seven-Tails (七尾, Nanabi), is a tailed beast sealed within Fū from Takigakure. It has been captured, extracted, and sealed by Akatsuki. In the anime, Chōmei is indicated to have been one of the two tailed beasts that Akatsuki captured before the start of Part II. It was later resealed into a reincarnated Fū during the Fourth Shinobi World War.

Gyūki
Gyūki (牛鬼, Gyūki), more commonly known as the Eight-Tails (八尾, Hachibi), is a tailed beast sealed within Killer B of Kumogakure after A's cousin, his cousin's uncle and cousin's father failed before him.

Kurama
Kurama (九喇嘛, Kurama), more commonly known as the Nine-Tails (九尾, Kyūbi), is a tailed beast currently sealed within Naruto Uzumaki of Konohagakure. The fox was first sealed into Mito Uzumaki after the battle at the Valley of the End, then into Kushina Uzumaki after Mito's death.