Naruto Uzumaki's Jinchūriki Forms

Naruto Uzumaki is the Jinchūriki of the Nine-Tailed Demon Fox. When Naruto taps into the demon fox's chakra, it increases every physical aspect of his body. He is gifted with near-limitless chakra and stamina, massive strength, increased speed, an almost impenetrable chakra shield, and accelerated healing. Naruto has unique access to the demon fox's chakra due to the seal that the Fourth Hokage placed on him. The seal split the demon fox's chakra in two halves, Yin and Yang, and sealed only the Yang chakra into Naruto. Minato states that he sealed half the fox's chakra in Naruto for two reasons: he believed that his son would be able to use the power of the demon fox, and the other that an extremely strong ninja was controlling the demon fox when it attacked Konoha; and that, a special power (like the demon fox's) would be needed in order to fight the shinobi.

Jinchūriki Form
By simply tapping into the demon fox's chakra, Naruto's blue eyes turn red, his pupils become slitted, his nails and canine teeth grow long and sharp, his blond hair becomes longer and spikier, and his whisker marks become feral scars. Depending on how much chakra is unleashed, the red chakra is capable of glowing around his body in an untamed way. Naruto first reached this form when Sasuke Uchiha was thought to be killed by Haku, overwhelming Naruto with rage and allowing the demon fox's chakra to leak out of the seal.

Even though this is the weakest state of his Jinchūriki forms, it is still a deadly foe as it increases Naruto's physical strength and healing well above most shinobi. This form also increases his speed to such high levels that nothing short of a fully matured Sharingan is able to track his movements. He can also use the chakra as a shockwave, sometimes merely using a roar or thrusting his fist out to send a rush of energy at his opponent. Until special training from Jiraiya, Naruto could only reach this state through rage or if his life was in imminent danger, but after having a inner talk with the demon fox, he is able to tap into the demon fox's chakra on his own (or by simply telling the demon fox to give him some power).

One-Tailed Transformation
During Naruto's battle with Sasuke at the Valley of the End, when Naruto was at the mercy of Sasuke, the demon fox told Naruto that he should be grateful to it and gave him more chakra. The amount of chakra is so great that it leaks out of his body in a denser state. All the physical traits of the basic Jinchūriki form are present and slightly altered, including black rings around the eyes, longer nails and canines, and more berserk looking eyes. This form also comes with an additional bonus; the red chakra becomes a complete shield around his body, in the shape of a fox, complete with long ears and a tail, known as the demon fox's cloak or shroud.

In his one-tailed transformation, Naruto fights more like a beast. Instead of using his fists, he uses his sharpened claws. In this form Naruto has also shown the ability like in his other forms to make a shockwave with a simple wave of an arm. While he can stand on his own two feet, he can move at greater speeds on all fours. His most powerful weapon is the chakra itself. The bubbling chakra appears to have a mind of its own: when a strike that was meant for Sasuke missed, the chakra itself stretched off Naruto's arm and hit Sasuke before he could react. Since the chakra is sentient, it is extremely difficult (if not impossible) to predict Naruto's movements. Sasuke was able to see Naruto perfectly, but couldn't predict the chakra's actions with his Sharingan. The chakra can also act as a shell to help Naruto create a Rasengan without the help of clones, the Rasengan called Demon Fox Rasengan. The chakra can also stretch far from the body, as when Naruto was shown using his "arms" to attack Sasuke from great distances. At one point he was on the opposite side of the valley and still attacking Sasuke with his chakra arms. The shield around his body grants him some measure of protection, enough that ordinary attacks like Fire Release: Great Fireball Technique will have no effect.

Two-Tailed Transformation
After catching the Akatsuki member, Deidara, and beating what he thought was Deidara to pieces only to realize he had been attacking a substitution, his anger at losing Deidara and not being able to avenge Gaara's death caused Naruto to slip into his two-tailed transformation. His physical characteristics match the first two forms, but his red eyes and canines grow larger, and his lips get a black outline, similar to fox gums. The chakra shield's only difference between the one-tailed transformation and the two-tailed is the extra chakra tail that has formed.

While in this state, Naruto is still in control of his body, though to what extent is unknown. In the anime, he punched a tree, destroying it and a long line of trees behind it. Later he attempted to attack Kakashi Hatake, who calmed him down and brought him back himself. The amount of chakra produced by the two-tailed transformation was so great that even Naruto's shadow clones doubled over in pain.

Three-Tailed Transformation
After Orochimaru revealed himself to Team Yamato and baited Naruto with news of Sasuke, Naruto went on a rage and first attacked him in his one-tailed state. When that failed, along with further baiting from Orochimaru, Naruto skipped the two-tailed transformation altogether, and went straight into his three-tailed transformation. The three-tailed state looks similar to the two-tailed state, but with the demon fox's features becoming more pronounced. His eyes later become similar to the four-tailed transformation, but can return to normal. The amount of chakra produced from this form is devastating. The very air around Naruto begins to hurt. This is the strongest form Naruto can reach and control. With the standard chakra shield's protection and attack power, a simple roar has the power to create a devastating sphere of destruction.

Four-Tailed Transformation
When Orochimaru further taunted Naruto about Sasuke, Naruto in a fit of fury and anger, slipped into the demon fox's grasp. The demon fox's chakra began to burn its way through Naruto's body, destroying his skin and rapidly healing it at the same time, eventually covering his entire body in a mix between the demon fox's chakra and his own blood. Everything from his face to his chakra tails became completely solid, his eyes losing its characteristics and becoming empty glowing circles surrounded by a black mask of chakra.

In this state, in effect, Naruto takes the place of the demon fox inside the cage. The demon fox has complete control over Naruto's body, making it a mere skeleton for the fox's chakra, and every living thing in its way a target. The four-tailed transformation has all the benefits of the other tails, with upgrades. With a simple wave of his hand, it can send a shock wave of destruction. The chakra shield, while being solid, still completely protects Naruto's body, and is so hot that it can burn the skin on contact. If Naruto is hit, the chakra itself can form another body, and strike back almost instantly. The demon fox also has the ability to charge a concentrated ball of chakra, consume it, and then fire it with such a force that it could destroy all three Rashomon gates. Finally, its chakra shield's defensive power is so great that even Orochimaru's legendary Kusanagi couldn't pierce it, only bending it slightly.

In the end, despite it being Naruto's strongest Jinchūriki form revealed up until his fight with Pain, the four-tailed transformation and all transformations stronger are Naruto's greatest downfall. Because the demon fox's chakra is constantly destroying and creating new cells, it also shortens Naruto's life, similar to Tsunade's Creation Rebirth. Also, because the demon fox has complete control, Naruto will attack anything that moves (including his friends). This discourages Naruto from using this state more than the fact that it shortens his life. Naruto first slipped into this state when he was training with Jiraiya, because he used the toadkey to "twist" the seal the Fourth Hokage placed on Naruto. A small "twist" of the seal unleashed the four-tailed transformation and almost killed Jiraiya. Naruto also requires healing immediately afterward, otherwise, due to his lack of skin, it would be nearly impossible for him to move through the fairly large amount of pain he goes through.

Six-Tailed Transformation
During Pain's invasion of Konoha and after Naruto's failed attempt to defeat the Deva Path, Naruto was left pinned to the ground when Hinata Hyuga challenged Pain in a desperate attempt to protect Naruto, knowing full well she could, and most likely would, die. Outmatched, Hinata was quickly dispatched, stabbed and severely wounded by Pain's Chakra Disruption Blades. Infuriated and believing Hinata to be deceased, Naruto lost control and exploded into his four-tailed transformation and quickly slipped into his six-tailed transformation, skipping the five-tailed transformation all together. The appearance of the sixth tail brings Naruto's body even closer to the demon fox, to the point where the demon fox's bones form out of the intense chakra around his body attached to the body with several thick chakra strings. The raw potency of its chakra is so great, that it completely rejected First Hokage's necklace's effects to repress it. The demon fox removed the crystal and crushed it. With its raw power the demon fox was able to withstand Pain's Shinra Tensei, then reflect the attack back upon Pain himself. A noteworthy feat, as even Gamabunta, along with two other toads of sizes equal to his own, had very little luck fending off Pain's force-based attacks. He also has a similar attack to Four-Tailed Fox Menacing Ball which is called Six-Tailed Fox Menacing Ball. Unlike the four-tailed form, the six-tailed form is able to unleash this blast without first injesting and presumably not affect his ability to manuever. Without even being fully charged the attack had enough energy to create a large crater next to the already destroyed Konoha. Despite this attack's power, it seems even at full power (presumably), the Menacing Ball is not strong enough to destroy the large sphere of earth made from Pain's Chibaku Tensei.

Eight-Tailed Transformation
As the demon fox fought Pain through the six-tailed transformation, Naruto within his consciousness thought of Pain's plans for peace and pleaded for someone to help him with a response. Through his suffering, the demon fox tempted him to destroy everything in the world that hurt him and to break the seal by saying that if Naruto gave his heart to it, then it would stop his pain. His influence caused the seal to "distort" and allowed the eighth tail to grow.

The eight-tailed transformation brings Naruto's body, as per the previous forms, closer to that of the demon fox. This form is his largest so far, and muscle tissue begins to grow on the bones from the six-tailed transformation. In this form, Naruto is about the same size as the demon fox, with the only things missing being the ninth tail, skin, and fur. The eight-tailed transformation was so powerful, that it broke through Pain's Chibaku Tensei with brute force.

The seal is arranged so that when the eighth tail forms, the spirit of Minato Namikaze appears within Naruto's subconscious.

The eight-tailed transformation is stopped and canceled out after Minato restores the seal, but it was stated by Minato that this was the last time he would restore the seal. So the fail safe concerning the transformation may be a one time deal.

Jinchūriki Chakra Control
In the event of the demon fox manifesting, Jiraiya gave Kakashi a special written seal that is to be placed on Naruto's body. This seal suppresses the demon fox's chakra and restores Naruto to his normal self. In addition, Yamato has demonstrated a technique that reverses Naruto's demon fox transformation, enhanced greatly by the First Hokage's necklace that Naruto wears. Naruto, in the anime, has shown that with enough will power, he is able to suppress the demon fox's chakra from taking over. However, the important factor to this is that the demon fox's chakra was responding to the vessel of its residual chakra so it is unknown if Naruto could use his willpower to suppress the demon fox's chakra if it forced its way in a similar fashion as his first four-tailed transformation (it should also be noted that this was part of a filler arc, and has no relation to the manga). It has also noted that during his fight with Kakuzu, Naruto's eyes were shown to have slitted pupils like the demon fox's, but in Naruto's blue eye color, perhaps showing strong chakra control over the demon fox.

Sasuke has also demonstrated the ability to forcefully suppress the demon fox's chakra. To parallel the demon fox's apparent connection with the Uchihas, Itachi Uchiha of Akatsuki was originally assigned to capture it as part of the organization's goal of obtaining all the Tailed Beasts. This task was later given to Pain.

The Seal which contains the demon fox within Naruto was designed with a fail safe attached to it. In the event that Naruto reached the eight-tailed state, Minato would appear inside Naruto's subconscious to protect him and the seal. It appears though that the fail safe is a one time deal though, as Minato states after he restores the seal that this was the last time he would do so.