Ten-Tails

The is the primordial entity tied to the legend of the Sage of the Six Paths. Its chakra was divided into the nine tailed beasts and its body sealed into what would become known as the moon, by the Sage in his final moments of life. The Ten-Tails is considered to be the creator of the world, and the herald to its end should it ever be revived. Obito Uchiha's ultimate ambition, which was created and designed by Madara Uchiha, the Eye of the Moon Plan, is to capture and merge all nine of the tailed beasts' chakra back into the Ten-Tails' body, and become its jinchūriki and then cast the reflection of his Sharingan on the moon, casting a genjutsu known as the Infinite Tsukuyomi which will put the entire world under his control.

Background
Centuries before the founding of the hidden villages, the Sage of the Six Paths saved the world from the Ten-Tails. He managed to subdue the beast and seal it within his own body, becoming the first jinchūriki. However, this offered merely a temporary solution to the menace: in the event of his death, the seal would dissolve and the Ten-Tails would once again be unleashed upon the world. Knowing this, the Sage searched for a more permanent solution. Ultimately, the Sage succeeded by using his Creation of All Things ability to separate the Ten-Tails' chakra from its body and divide it into nine separate constructs that would later become known as "tailed beasts", scattering them throughout the world. As a final precaution, using Chibaku Tensei, the Sage entombed the physical remains of the Ten-Tails within a colossal stone prison and hurled it into the heavens, creating the moon. The astonishing feat of not only successfully sealing the Ten-Tails, but also suppressing it, made the Sage a deified hero throughout the shinobi world.

Centuries later, the Rinnegan would once again manifest itself in one of the sage's descendants: Madara Uchiha. With his new power, Madara summoned the empty vessel of the Ten-Tails back into the world and named it the Demonic Statue of the Outer Path. Joined by Obito Uchiha, who continued his work after his natural death, Madara devised a means to reunite the Demonic Statue and the tailed beasts back into their one original form so he can use the Ten-Tails to enact his life-long objective: the Eye of the Moon Plan.

Personality
As noted by Kurama, the Ten-Tails lacks a consciousness to possess feelings or ideals, thus making it impossible for those to sense it through such means as those that involve detecting negative feelings or chakra. People in Sage Mode are best able to gain some sense of the beast's power, and even then it appears unmeasurable and overwhelming; Kurama likens the Ten-Tails to be an innate force of nature. But the Ten-Tails appears to be a sapient being to some extent as it reacted to seeing the presence of the tailed beasts chakra inside Naruto and the image of the Sage of the Six Paths by gathering chakra and strengthening itself.

Appearance
Silhouetted prior to its introduction in the story line, the Ten-Tails is a cyclops-like humanoid in appearance with a conch shell-like upper body with long, spiked-like protrusions on its back. Its unique red eye, taking up most of its head, has four concentric circles with nine tomoe in the three circles closest to the pupil. In a later appearance, the Ten-Tails' look was a bit more "crass". The spiky protrusions on its back were much higher, resembling a conch shell, and its tails were bushier. It appears to have a tan skin colour.

For unknown reasons after its revival, it was brought back with six tomoe in its eye instead of nine, the Ten-Tails appeared in what Madara and Obito revealed to be its larval stage. In its immature form, the Ten-Tails possessed a grotesque bulb-like body much larger than Gyūki and Kurama, with spiky protrusions growing out of its back, and a wide, cavernous mouth with multiple rows of sharp, pointed teeth, as well as a spiked chin. It had long arms and clawed hands, but no visible hind-legs. It also had dark veins similar to those of a plant all over its body, and the endings of its tails resembled leaf buds, which had been shown to unfurl as the beast matured.

After further maturing, the Ten-Tails more closely resembled its humanoid silhouette from the flashback. Its bodily proportions were very elongated, and emaciated with a twisting neck, yet it retained the spiked bulb from its previous form on its back. The beast possessed visible legs, which it used along with its right arm to stand, as its left arm was missing at the elbow. Its facial appearance changed greatly, growing a single ear on the right side of its head, while its mouth, which now contained straight teeth, moved to the left side and several horns formed on various parts on its head. The monster's tails now end with hands similar to the chakra arms formed by jinchūriki.

As it continued to mature, the Ten-Tails gained a more muscular, healthy appearance, grew a complete left arm, giving it the ability to form hand seals by clapping its hands together, and began standing on its hind legs once more. After gathering more chakra, it begins to evolve further by assuming an even more muscular form and its horns grew longer. In this form, the Ten-Tails can open its mouth wide to reveal a rafflesia arnoldii-like appendage when later using a Tailed Beast Ball. The bulb on its back has also become much smaller.

Abilities
As the original form of all nine tailed beasts, the Ten-Tails was said to possess massive and overwhelmingly foul chakra that is potent enough to bring total despair and destruction to the world. Not only is the Ten-Tails the source of all chakra, but also the progenitor of everything that exists in the world. It is a god that created countries and has the power to swallow oceans, split the land, and carry mountains. In addition, Kurama admitted that it alone wouldn't even stand a chance against the Ten-Tails, and stated that the Sage told them that its revival would result in the end of the world. When Naruto Uzumaki attempted to use Sage Mode to gauge the power of the beast, he was overwhelmed by the vastness of the beast's power, which Kurama noted as immeasurable. Its power was reaffirmed when the beast's chakra completely warped the shape of the Sensing Water Ball at Allied Forces HQ into two connected spheres. It has been stated by Gyūki that if the Ten-Tails was allowed to reach its final form, then there would be no chance of defeating it.

As the original Tailed Beast, the Ten-Tails can create a Tailed Beast Ball. In the beast's initial form, the ball is fired as a continuous beam and is able to overwhelm multiple Tailed Beast Balls from both Gyūki and Kurama without losing momentum; all while still damaging six of Kurama's tails and causing a trail of destruction across the landscape. When the Ten-Tails matured into its second form, its Tailed Beast Ball took on a unique, cone-like shape and gained an immense increase in range, firing speed and destructive power, capable of destroying mountain ranges and entire cities with a single shot. After gathering a considerable amount of chakra and undergoing several transformations, the Ten-Tails later unhinged its jaw to unfurl a rafflesia-like mouth that functions as a cannon capable of firing massive and extremely powerful Tailed Beast Balls.

Even in an incomplete state, the Ten-Tails possesses immense physical strength and is remarkably fast, despite its tremendous size, as it was able to attack both Naruto and Killer B before either of them could react. It casually flicked back a Tailed Beast Ball with one of its fingers. The beast has extreme durability and can remain unfazed even after sustaining massive damage, with a combined Tailed Beast Ball from both Gyūki and Kurama not harming it. A single swipe of its tail was enough to tear up the landscape around it. Obito noted that it could even withstand the backlash of its own Tailed Beast Ball fired at point-blank range, though Madara believed that the beast would still be wounded. Obito's assumption was proven correct when the Ten-Tails' Tailed Beast Ball, along with Gyūki's, detonated inside of its body, causing it to briefly inflate before shrinking back down largely unaffected. It could also regenerate its tails after they were cut.

In its second form, the beast's tails become elongated arms, which effortlessly broke free from the various restraints created by the Allied Forces. The beast seems capable of freely expanding the length and thickness of these tails, using them in order to attack distant foes. Its single eye is able to see across extremely vast distances, and can see chakra. After further amassing its chakra, the Ten-Tails' roar can stir a series of massive natural disasters.

When restrained by Hashirama Senju, it split into several Ten-Tails Mini Clones to avoid being captured. They are of many shapes, some larger than others, and some with weapon like appendages on their arms. Obito Uchiha was able to use the beast as a medium for his Wood Release: Cutting Technique.

Ten-Tails Revival Arc
Though only able to obtain fragments of Gyūki and Kurama's chakra, Obito Uchiha begins the Demonic Statue of the Outer Path's regeneration into the Ten-Tails. As Madara Uchiha joins the fray, Naruto and Killer B attempt to wipe out the Demonic Statue with a massive Tailed Beast Ball to stop the Ten-Tails from being fully revived. Though the statue's chakra vanished after the attack, the allied ninja's victory was short lived as the Ten-Tails emerges from the settling smoke. With this, Obito echoed Kakashi's sentiments that it was in fact the end, of this world and not the battle. Elsewhere, though disappointed that he was not able to capture the Eight and Nine-Tails to complete the beast's revival, Madara castes this aside and noted that they needed to get on with the plan.

With the revival complete, Obito and Madara situated themselves atop the beast, from which two tendrils manifested and connected themselves to the two Uchiha. Not wanting to waste any time, Obito noted that he wanted to cast the Infinite Tsukuyomi immediately while Madara wanted to test the beast's power first. As the beast attacked Gyūki and Kurama, it quickly landed a blow on Kurama before the fox had time to retaliate. Landing on either side of the beast, Kurama and Gyūki launched a barrage of simultaneous Tailed Beast Balls at the beast only for the Ten-Tails to counter using one of its own, completely nullifying the oncoming attacks. After the dust cleared, a Naruto shadow clone and Kakashi appeared above the Ten-Tails where Kakashi released Gyūki who was preparing to launch a point-blank range Tailed Beast Ball.

Merely flicking the ball back at Gyūki with a finger, the beast prepares to crush Kakashi and Naruto beneath its tail, but only manages to dispel the shadow clone as Kakashi was pushed to safety. Afterwards, the Uchiha have the Ten-Tails prepare a Tailed Beast Ball to decimate their severely exhausted opponents but much to everyone's shock, it missed. It is revealed that control of the beast had been momentarily wrested from their control. With the battlefield now shrouded in mist and all sensory skills being jammed, the question of whether they thought they were hiding was raised. With a single swipe of its tail, the beast is able to dissolve the mist. Just then the Wind Release: Wind Cutter Technique is used to counter, and when the mist cleared, it is revealed that the rest of the Allied Shinobi Forces had joined the battle.

The Alliance launched a barrage of techniques in order to incapacitate the Ten-Tails, so that they could get to Obito and Madara. As the beast is subsequently immobilised in what was effectively cement, the two Uchiha commented that the effort is futile as the Ten-Tails began its metamorphosis into its mature form. Once fully matured, the Ten-Tails bursts forth from its prison and proceeds to devastate several towns, with the shinobi headquarters and everyone in it targeted as well. After wiping out the headquarters, Madara realises that Ten-Tails is becoming more troublesome to control as he allows Obito to assume command as only he can revive Madara into a living body, allowing him to become the beast's jinchūriki. Once in control, Obito uses the Ten-Tails to channel the Wood Release: Cutting Technique to decimate the Allied Forces with wooden stakes, with Neji Hyūga among the fatally wounded, before it is sandwiched between Kitsuchi's Earth Release: Sandwich Technique. When encouraging words from his friends kept Naruto from breaking, Obito ignoring Madara that he would injure the Ten-Tails wrapped the beast with its tails and prepared to annihilate the Allied Forces with a Tailed Beast Ball at close range. However, before the ball could be fired, Killer B transformed into the Eight-Tails charging his own Tailed Beast Ball, stuffed both into the Ten-Tails' mouth and detonated them, causing the beast to collapse in pain.

After Naruto infused Hinata Hyūga with Kurama's chakra, she was able to deflect one of its tails before Naruto sent his shadow clones to repeat the process with other Alliance shinobi. Overwhelmed by the empowered Allied ninja, the Ten-Tails was restrained by Shikamaru Nara and his Nara clan kinsmen. With Madara's influence, the Ten-Tails was able to resist the Shadow Imitation Technique and attempted to assault the Alliance shinobi with its tails, only to be stopped by their combined efforts. The beast subsequently formed a cage around the Alliance as Obito mocked that it was a fitting fate akin to what the Hyūga subjected its members to. Not deterred by this, the shinobi press forward and cut through their would be bars with Naruto's Rasenshuriken. Naruto was able to force Obito to avoid his Rasenshuriken while Rock Lee attacked Madara, causing the two to lose their means of controlling the beast as they are forced to the ground. However, now acting on its own mindless accord, and maturing even further, the Ten-Tails went on a rampage while completely warping the weather around the area. Obito considered becoming its jinchūriki to contain it, but ended up being caught into battle with Kakashi, going into the other dimension. After the Tenpenchii dissipated, it looked at Naruto and sensed the presence of eight tailed beasts, and saw mysterious shadow with a pair of Rinnegan. This stirred it and it roared while gathering more chakra, increasing its form once more. It opened its mouth wide, producing a flower-like structure that it used to create a large Tailed Beast Ball, firing it at the Shinobi Alliance. It easily smashed through their Earth Release barriers, but was warped away by Minato Namikaze upon his arrival to the battlefield.

After the reincarnated Hokage have properly positioned themselves, they trap the Ten-Tails within a large barrier topped with Hashirama's restraints to further immobilise its movements as they prepare to attack the beast. The Ten Tails, aware that it's capture seems imminent, splits into Ten-Tails Mini Clones, charging Naruto and Co.

Trivia

 * Deidarabotchi, also known as, was a yōkai of titanic proportions in Japanese mythology. Kurama's explanation of how powerful the Ten-Tails is reflects Daidarabotchi's role in the formation of Japan's wilderness, such as the two peaks of Mount Tsukuba, according to Japanese myth.
 * The name "Datara" may refer to, a one-eyed, one-legged blacksmith said to live deep in the mountains of Kumano. Myths vary on his nature as a yōkai or the fallen deity Ameno-me-Hitotsu. Either way, the legends say of Ippon-datara's ability to forge living things from metal that makes another reference to the Ten-Tails as the progenitor of the world.
 * In its début in the anime, the Ten-Tails was shown with its red eye with nine tomoe during its battle with the Sage of Six Paths, but when it was about to be sealed into the moon, its eye was purple like the Rinnegan and was missing the tomoe. These were later corrected in episode 253.
 * However, when Madara used a genjutsu to tell Obito the story of the Ten-Tails, the mural that depicts the beast has six tomoe in its eye instead of the previously established nine.
 * The Ten-Tails can be revived without fully collecting all nine tailed-beasts, having a fraction of the chakra of which is enough to revive it in an incomplete form. However, even without the other tailed beasts the Ten-Tails will slowly become its former self, though it takes time for it to "mature" into its complete form, making it harder for Madara and Obito to control it as it does.
 * The second form of the Ten-Tails head has three primary features: an eye, an ear and a mouth. This is possibly a reference to the maxim: "see no evil, hear no evil, speak no evil", alluding to the fact that the beast is not inherently malevolent, but is actually being used for nefarious purposes by Madara and Obito.