Jinchūriki

The are humans that have a tailed beast sealed within them. They exhibit extraordinary powers, and in some cases are more powerful than their tailed beasts, because they have the intelligence to use the beast's powers effectively.

The first jinchūriki was the Sage of Six Paths, who sealed the Ten-Tailed Beast within himself to save the world, but before his death, the Sage divided the Ten-Tails' chakra into nine separate tailed beasts and sealed the Ten-Tails' body into the moon. By the time of the formation of the shinobi villages, Hashirama Senju, the First Hokage, used his Wood Release techniques to capture and give several tailed beasts to the other shinobi villages as peace treaties, in order to stabilize the balance of power between them, but after Hashirama's death, the villages had trouble containing the beasts. The Second Kazekage of Sunagakure was the first to research the jinchūriki, with the other villages following soon after, with hopes to use the beasts as weapons in human hosts, or in Konoha's case, keep the beasts from doing harm to their village. In order to prevent the jinchūriki from turning traitor, it is tradition for the host to be selected from the family of the village's own Kage. In this way, the jinchūriki not only has strong ties of loyalty to village and their leader, but they also serve to show off the Kage's might. For example, Gaara is the son of the Fourth Kazekage, Killer Bee the brother of the Fourth Raikage.

Each village has used a different seal when creating their jinchūriki. For example, the Fourth Hokage used the Eight Trigrams Sealing Style, and Kumogakure's Killer Bee has an Iron Armor Seal. Akatsuki, an organization whose role in the series is to capture the jinchūriki, uses the Illusionary Dragon Nine Consuming Seals to extract the tailed beasts, and seal it away for future use. They have, as of the Fourth Great Shinobi World War, captured seven of the nine beasts.

The seal that keeps a tailed beast within its host is at its weakest when a female jinchūriki is in childbirth, due to the nurturing of the child in the womb using the power of the seal, weakening the seal in direct proportion. As such during childbirth, a ninja is required to keep the seal intact and also to restore the seal back to full power after the birth. A full term pregnancy for a female jinchūriki is about 10 months, presumably because the body has to nurture both the child and the seal simultaneously, as a result the child develops more slowly.

Personality
Jinchūriki are typically lonely people, viewed by those around them as the beast that has been sealed within them, leading to prejudice and being hated and feared. According to Akatsuki, the first two jinchūriki they captured loathed humanity, and their villages were in fact glad to be rid of them. However, certain jinchūriki refuse to waver, despite being shunned, instead having a cheerful demeanor, and eventually earning respect. Such examples are Killer Bee and Naruto Uzumaki.

As the jinchūriki draws on more of their beast's power, their personality tends to corrode into animalistic instincts. Because most of the tailed beasts' survival depends on their hosts' safety, they are very protective, and will act whenever their hosts' lives are in danger. However, this is not always the case; the Nine-Tails, before it was sealed into Naruto, was said that it can survive its host's death, with the only consequence being that it would take time for it to be revived. Normally, these hosts have little control over themselves as they transform deeper into their tailed beast forms, and become more beastly in battle. However, Yagura and Killer Bee are the only jinchūriki to have full control of their tailed beasts, can retain complete consciousness and control even after a full transformation.

Abilities
Jinchūriki have shown to have access to great amounts of chakra and access to unique fighting styles, depending on their tailed beast: Gaara controls sand, Yugito controls fire, Rōshi controls lava, Killer Bee can spit ink, and Naruto has high stamina and quick rejuvenation. By training, they can gain additional access to their tailed beast and its chakra, such as Killer Bee being able to synchronize with his beast, and transform himself into it, and Naruto, who sectioned off the Nine-Tails' chakra, accessing it only when he needs it, giving him a chakra shroud resembling the Sage of the Six Paths. Tailed beasts can also provide its hosts with constant advantages, such as Gaara's self-activating Shield of Sand which automatically protects him, even from self-injury; and Naruto's healing factor that immediately activates as soon as he incurs wounds.

Not all jinchūriki can retain control when they transform into their tailed beast. Before his training in the Falls of Truth, when Naruto reached his four-tailed form, he lost the ability to discern between friend and foe, and attacked anything in sight. Gaara, even before he started to take Shukaku's form, was constantly plauged by his beast, causing insomnia, a trait that all of Shukaku's hosts share.

List of Jinchūriki

 * One-Tailed Shukaku
 * First Shukaku Jinchūriki
 * Affiliation: Sunagakure
 * Status: Extracted and sealed within second jinchūriki; deceased
 * Second Shukaku Jinchūriki
 * Affiliation: Sunagakure
 * Status: Extracted and sealed within Gaara by Chiyo; deceased
 * Gaara
 * Affiliation: Sunagakure
 * Status: Captured and extracted by Akatsuki; later revived by Chiyo


 * Two-Tailed Monster Cat
 * Yugito Nii
 * Affiliation: Kumogakure
 * Status: Captured and extracted by Akatsuki; deceased


 * Three-Tailed Giant Turtle
 * Yagura
 * Affiliation: Kirigakure
 * Status: Extracted under unknown circumstances; deceased


 * Four-Tailed Monkey
 * Rōshi
 * Affiliation: Iwagakure
 * Status: Captured and extracted by Akatsuki; deceased


 * Five-Tailed Dolphin Horse
 * Han
 * Affiliation: Iwagakure
 * Status: Captured and extracted by Akatsuki; deceased


 * Six-Tailed Slug
 * Utakata
 * Affiliation: Kirigakure
 * Status: Captured and extracted by Akatsuki; deceased


 * Seven-Tailed Horned Beetle
 * Fū
 * Affiliation: Takigakure
 * Status: Captured and extracted by Akatsuki; deceased


 * Eight-Tailed Giant Ox
 * Previous Eight-Tails Jinchūriki
 * Affiliation: Kumogakure
 * Status: Extracted by the Third Raikage, sealed within a pot, and then sealed within Killer Bee; deceased
 * Killer Bee
 * Affiliation: Kumogakure
 * Status: Active


 * Nine-Tailed Demon Fox
 * Mito Uzumaki
 * Affiliation: Uzushiogakure, Konohagakure
 * Status: Extracted and sealed within Kushina; deceased
 * Kushina Uzumaki
 * Affiliation: Uzushiogakure, Konohagakure
 * Status: Extracted by Madara Uchiha, and then sealed within Naruto by Minato Namikaze; deceased
 * Naruto Uzumaki
 * Affiliation: Konohagakure
 * Status: Active


 * Ten-Tailed Beast
 * Sage of the Six Paths
 * Affiliation: Unknown
 * Status: Separated its chakra into the nine tailed beasts and trapped its body in the moon; deceased

Similar Cases
In the anime, Sora only had a part of the Nine-Tails' chakra sealed into him, which made him a "pseudo-jinchūriki". Even though he was granted similar abilities to those of a real jinchūriki, his were vastly inferior.

In Naruto Shippūden 2: Bonds, Amaru had the Zero-Tailed Masked Leech sealed within her, but because the Zero-Tails is not an actual tailed beast, Amaru is not considered a jinchūriki.

In the anime, Yūkimaru had the ability to control the Three-Tails. While his appearance is similar to that of Yagura, the Three-Tails' former jinchūriki, with the same distinctive eye and hair color, no confirmed connection exists between the two. The tailed beast was not actually sealed inside of him, and, thus, he was not a real jinchūriki.

Trivia

 * Gaara died when Akatsuki removed Shukaku from his body, but he was later revived by Chiyo. Although he no longer has Shukaku sealed within him, he can still control sand. It is unknown if other jinchūriki would have kept their powers under the same circumstances had they survived their beast's extraction.
 * Kushina Uzumaki was the only jinchūriki known to have survived the extraction of her tailed beast, due to her clan's vitality.
 * Takigakure is the only village not belonging to one of the Five Great Shinobi Countries known to have had a jinchūriki.