All jinchūriki are able use certain abilities granted to them by their tailed beasts. As they get older and they gain (or lose, as the case may be) control over their tailed beast, they are also able to transform into their tailed beast to varying degrees, granting them capabilities increasingly closer to the tailed beast itself.
Initial Jinchūriki Form
By simply tapping into their beast's chakra, a jinchūriki begins their initial transformation. They are surrounded by a layer of red, wispy chakra and are granted enhanced strength and speed. The beast's chakra supplements the jinchūriki's and they are able to manipulate the chakra to a certain extent: Utakata can form the it into waves and blasts while Naruto can thrust it outwards with his fist or emit it as a roar. In this form the jinchūriki's body undergoes slight physical changes, notably their eyes change color and become slitted. Nails and canine teeth may grow longer and sharper. In the case of Naruto, his hair grows longer and spikier and his whisker marks widen and thicken.
Version 1 – or what Jiraiya calls Naruto's "demon fox cloak" (妖狐の衣, yōko no koromo) – forms a dense shroud of chakra around the jinchūriki. The shroud, a translucent red with bubbles of chakra (reminiscent of boiling liquid) forming all along it, provides a degree of physical protection. The physical changes experienced in the initial transformation become more pronounced in version 1 forms.
The shroud that encompasses the jinchūriki vaguely resembles the corresponding tailed beast; paws of chakra form around their hands and, in the case of Killer B, chakra-horns form on his head. Because chakra is malleable, the shroud can extend beyond the reach of the jinchūriki, often used to create chakra-arms that allow them to interact with their environment. The most significant manifestation are the tails that sprout from the jinchūriki's body, up to the maximum number of tails that the corresponding beast possesses. As with the chakra-arms, these tails can aid the jinchūriki by grasping to their surroundings. For each tail produced, the jinchūriki gains an incrementally greater boost to speed, strength, and of course chakra.
The source of the chakra shroud differs between users. For jinchūriki who have not learned how to control their tailed beast, it is the beast's chakra that surrounds them. The beast's chakra will tend to be harmful: individuals near the jinchūriki will experience a slight physical discomfort; those who come into contact with the shroud will suffer a painful burn wherever they touch it; the jinchūriki themselves suffer an increasing amount of corrosion to their body that can eventually damage body parts beyond the point of use. This shroud is typically acquired through a growing rage and/or the seal that keeps the beasts within their body weakens, and consequently leaves the jinchūriki less in control of their body with each additional tail. While a jinchūriki has never been observed to completely lose control of themselves in a version 1 form, they become more animalistic and aggressive. One advantage of this is that the the shroud can act on its own, responding to threats the jinchūriki may not be aware of.
A secondary means of entering a version 1 state is demonstrated by Killer B, who uses his own chakra in the shroud's formation and thereby grants him full control of when and where chakra-appendages form. This also prevents the harmful chakra and diminishing control experienced when using the beast's chakra. Naruto also becomes able to avoid these shortcomings by taming the Nine-Tails and having it freely give its chakra to him; while Naruto has been able to communicate with the Nine-Tails and ask for a donation of chakra for several years, this always carried the above consequences until Naruto and the Nine-Tails were able to start working together. Although Naruto has not used this harmless version 1 for himself, he has been able to transfer it to others and thereby grant them all of the form's benefits.
- Known users: Yugito Nii, Yagura, Rōshi, Han, Utakata, Fū, Killer B, Naruto Uzumaki, Kinkaku and Ginkaku, Sora (anime only)
Whereas version 1 may or may not use the tailed beasts chakra, version 2 (バージョン2, Bājon Tsū) always does. Sabu describes version 2 as the beast's chakra being formed into a human shape, granting the jinchūriki an edge in battle without completely releasing the beast itself. Using the jinchūriki's body as a sort of endoskeleton, a dark red, nearly black layer of chakra envelops them. The physical manifestations of the corresponding beast that are vaguely present in version 1 states become far clearer in version 2, in a way fully reproducing the beast in miniature: muscle mass increases and beast-specific attributes such as shells and ears become clearly defined. Because the shroud forms so tightly around them, features of the jinchūriki may be identifiable in version 2, such as the hat and furnace that Han wears.
Entering version 2 creates a great deal of energy, producing craters beneath the jinchūriki and destroying any restraints that might have been placed upon them beforehand. The shroud remains a reliable defense against attacks, strength, speed, and chakra are once again increased beyond the levels of the previous forms, and other features, such as chakra-arms, are still accessible. It is even possible for the jinchūriki to create chakra-bones around themselves: Killer B creates a bull's skull in order to perform a more powerful Lariat; Naruto, on different occasions, forms a full skeletal structure in differing states of completeness all along his body that are attached to him by chakra-ligaments, but the bones serve no obvious purpose.
Most jinchūriki have only been seen to enter a version 2 state with the same number of tails as their corresponding beast. Kinkaku, and by extension Ginkaku, represent one exception in that not only do they not have a full set of nine tails, but one tail remains far longer than all the others. Naruto is also an exception, for he has only been seen in a version 2 state with four, six, and (in the anime) seven tails. Unlike how the number of tails in version 1 can measure the jinchūriki's strength, there is no observable correlation between the number of Naruto's version 2 tails and his destructive capabilities. Likewise, although all jinchūriki gain unique, heightened abilities that bring them even closer to their corresponding beast, only Naruto (and Sora) have been shown performing a Tailed Beast Ball in a version 2 form.
Naruto has yet to knowingly enter a version 2 form. As the seal that kept the Nine-Tails contained weakened over the years, he became increasingly susceptible to its influence. By fully submitting to the beast and his own rage, Naruto would grant the Nine-Tails full control of his body who then formed a version 2 shroud around him. Naruto's ability to distinguish between friend and foe vanishes and he attacks in whatever way will enable him to defeat his target, oblivious to the consequences of the attack. The form itself carries a number of consequences for Naruto too, as its corrosive qualities burn away his skin and stain the shroud with his own blood. The regenerative abilities granted to him as the Nine-Tails' jinchūriki constantly heal the damage, but in the long run shorten his lifespan through the constant destruction and creation of cells. Sora's version 2 is also triggered by rage and causes the same kind of damage to his body. Kinkaku and Ginkaku appear to trigger version 2 through rage as well, but they retain control of their minds and do not seem to suffer any damage to their bodies.
- Known users: Gaara, Yugito Nii, Yagura, Rōshi, Han, Utakata, Fū, Killer B, Naruto Uzumaki, Sora (anime only)
Rather than fully transform into their respective beast, jinchūriki can isolate the transformation to parts of their body. Instead of appearing as clear or dark chakra, these partial transformations fully resemble the beast's, having fur, scales, etc. The jinchūriki reincarnated and controlled by Tobi each briefly partially transform but, other than Fū's ability to fly with her wings, they serve no purpose on this occasion.
Killer B makes a much more deliberate usage of the body parts he chooses to partially transform. He often produces extra tentacles to increase his ability to interact with others and his surroundings as well as to improve his dexterity. He has transformed one of his arms at different times, either to increase the distance that he was able to throw or to block a punch. In the anime, Sora unknowingly changes his right arm into a demonic form, but it bears no resemblance to the Nine-Tails'.
Naruto's partial transformations have been the most substantial of those seen. In order to break free of Chibaku Tensei, he entered a state just short of a full tailed beast-transformation (which, at the time, would have required completely breaking the Nine-Tails' seal); the only features it lacked to fully resemble the Nine-Tails were a ninth tail, skin, and fur, his transformation otherwise matching the beast's size and possessing all of the other chakra-body parts. After becoming able to harmonize with the Nine-Tails his partial transformations are less drastic, producing only tails like the other jinchūriki tend to or a head for attack.
Gaara represents an anomaly in the pattern of jinchūriki partial transformations. Whereas all other jinchūriki's transformations are composed of chakra, Gaara's is made of sand. He gradually piles sand onto his body, giving him an increasingly closer similarity to the One-Tail with changing eyes to match. In many ways it is similar to version 1 forms: his defenses are nigh-impenetrable wherever the sand is applied; he can stretch his sand-limbs beyond their normal reach; the more his body is covered with sand, the more his speed and strength grow. Being sand, he can detach parts of his "body" from himself that will retain their shape for as long as he exerts the chakra to maintain them.
Tailed Beast Mode
In principle, all jinchūriki can fully transform into the tailed beast sealed within them when the seal breaks and they entirely lose control over the beast. However, doing so results in the jinchūriki's death. Tailed Beast Mode (尾獣モード, Bijū Mōdo) is a way to avoid this. By either subjugating their tailed beast or learning to work in unison with it, a jinchūriki can become a scale-replica of the beast with complete access to its natural strength and abilities. If they choose, the jinchūriki can pass control of this form to the beast itself.
Tailed Beast Mode is devastatingly powerful and poses an untold risk of collateral damage. It is for this reason that Killer B is forbidden to use the form under normal circumstances, as it could easily destroy an entire ninja village if left unchecked. The most dangerous ability available to this mode is the Tailed Beast Ball.
Naruto has not been able to fully recreate the Nine-Tails' form. At first this was because the Nine-Tails would not cooperate with him, causing all attempts to turn into it to result in a miniature, comical version of the beast that could not be maintained for very long. Since then he has been able to earn the Nine-Tails' cooperation, but the "Tailed Beast Mode" he enters, though accurate in size, does not as closely resemble the beast as the other jinchūriki do their own. For more on Naruto's version of this form (and Minato Namikaze's) see Nine-Tails Chakra Mode.
- Naruto's miniature nine-tailed fox form resembles his true form from the Naruto manga pilot.
- In the spin-off manga Rock Lee no Seishun Full-Power Ninden, after Naruto and Rock Lee switch bodies due to one of Ino Yamanaka's jutsu, Lee entered a Version 1 state and instead of having the traditional tails, the chakra tails instead extended off of Lee's eyebrows.
- When Naruto first encountered Nagato face to face, he was shown to be able to simultaneously fuse his initial and Sage Mode forms together. His eyes took on the combined appearance of a mixture of them both. The exact capabilities of that form are unknown, but it was enough to completely resist Nagato's control of his Chakra Disruption Blades when it impaled Naruto.
- In Naruto Shippūden 2: Bonds, while fighting the Zero-Tails, Naruto was able to use the chakra arms of his demon fox shroud as makeshift wings for semi-flight.
- When Nagato absorbed some of Killer B's version 2 chakra, it returned him to his appearance before he had used the Summoning: Demonic Statue of the Outer Path technique.