Six Paths of Pain

The is an Outer Path technique possibly created by Madara Uchiha. Nagato was the first to use this technique after being crippled by Hanzō, and rendered emaciated from the numerous chakra receivers embedded in his back by the Demonic Statue of the Outer Path. By piercing corpses with chakra receivers, a wielder of the Rinnegan can manipulate the bodies as though they are their own.

As Pain, Nagato mainly used the Deva Path in presenting himself to the Akatsuki, while using it along with the others in battle. Though he controlled the bodies as extensions of his will, Nagato still saw his vessels as separate individuals from himself. Obito Uchiha would later adopt this fighting style and create his own Six Paths of Pain during the Fourth Shinobi World War using the reincarnated jinchūriki.

Use
Each of the six bodies used for the technique are pierced with chakra receivers, which allow the user to transmit chakra to them from afar. Nagato who used corpses as his Six Paths, transmitted chakra to them from the large black rods protruding from his back. Tobi seemingly did not need to implant the receivers into his body as his Paths were reincarnated individuals. The chakra being transmitted is then picked up by the chakra receivers that each body possesses, which can be fashioned into body piercings or completely hidden from view. To make full use of the bodies, the user would ideally control them from the highest and closest point possible, so that they could have the best possible range. With Nagato's usage of the Six Paths, certain techniques, such as Chibaku Tensei, were only available for use through the bodies when they were within a certain range of him. He was also able to increase the power of one of the Six Paths by focusing solely on it, although this would leave the others vulnerable and slow to recover. Inoichi Yamanaka compared this technique to the Yamanaka clan's unique Mind Body Switch Technique, albeit on a greater scale.

Nagato's Paths
Because of the fact that he was crippled, Nagato channelled the abilities of the Six Paths into six different bodies (one ability per body). The only common features shared by these bodies were the Rinnegan they gained from this technique, the chakra receivers each were pierced with and their bright orange hair, which had been dyed to match the Deva Path's natural hair colour. Each body seemed to serve a specific purpose in battle, such as summoning, repair, and defence, rendering them open in other areas. This did not hold true for the Deva Path, however, which was imbued with several capabilities. Each Path, with the possible exception of the second Animal Path, was in some way affiliated with Jiraiya when they were alive.

When the Paths were active together in battle, Nagato was able to see through their eyes, thus registering six separate fields of vision at the same time. Essentially working as shared vision for the Paths, this allowed Nagato to coordinate their attacks and to provide defence for them without a blind spot. His vision was also linked with the King of Hell and the creatures summoned by the Animal Path. Although they were limited to only one of the Rinnegan's Six Paths techniques, as well as its ability to see chakra, all of the Paths demonstrated incredible speed, strength and the ability to create chakra disruption blades, which were used to incapacitate opponents. The Paths were strongest when together, using combination tactics and the element of surprise to defeat their enemies; both Jiraiya and Kakashi fell victim to this technique. In the anime, it was shown that the Paths do not feel pain, and have cold skin. When the Paths were lined up in formation, the Deva Path was always in the centre, while the Naraka Path stayed in the back. This was to protect it, so it could revive the others who had fallen. However, his technique, although powerful, had a flaw: each of the Paths had a primary function or ability. With prior knowledge about the technique and each Paths' abilities, one stood a better chance of defeating them, as witnessed in Pain's battle against Naruto.

When not in use, the bodies were stored in a hidden chamber within Amegakure's tallest tower. Within the room are six "pods", in which the bodies rested; each pod is connected to the wall via pipes or wires, and has a sliding cover that appears to feature the symbol of Amegakure, which conceals the face of the inactive body. The pods are also numbered from one through six using daiji characters, and are ordered counter-clockwise around the room with a numbering scheme that corresponds with the ordering of the six Buddhist Paths of Reincarnation:
 * - Deva Path.
 * - Asura Path.
 * - Human Path.
 * - Animal Path.
 * - Preta Path.
 * - Naraka Path.

Obito's Paths
Taught to him by Madara, and only put to use during the Fourth Shinobi World War, Obito Uchiha, utilised his own version of this technique, using the six reincarnated jinchūriki. He customised them to fit his own taste, giving them each a Rinnegan and Sharingan in place of their left and right eyes respectively, mirroring those of his own. Unlike Nagato, Obito controlled his Six Paths using just a single chakra receiver embedded into the left side of each of their chests, which were hidden from view. He was also able to transmit chakra to his Six Paths without being pierced by chakra receivers as Nagato was. Each of the reincarnated jinchūriki could use the abilities they had during their life, such as Rōshi's Lava Release and Utakata's Soap Bubble Ninjutsu. However, thanks to Obito's augmentations, their skills were increased to beyond what they ordinarily were. With the Sharingan, they could now see through the most minute details of enemy movements, allowing for more precise attacks, and using the shared field of vision granted by the Outer Path of the Rinnegan, the user could coordinate these enhanced attacks in the most effective way possible.

The jinchūriki also had their respective tailed beasts temporarily resealed within them using the chakra receivers, while the beasts' chakra still remained under Obito's control through the Demonic Statue of the Outer Path. Although Obito could force the jinchūriki to transform into their full tailed beasts, a large amount of chakra was required to fully control the beasts, significantly increasing the risk of them subverting his commands. As a consequence of this, coupled with the fact that the abilities and their weaknesses were already known to his opponents, Obito did not have his Paths use the abilities of the Six Paths Technique.

Influences
Based upon the six Buddhist Paths of Reincarnation, each body was named after one of the different "Paths": Deva, Asura, Human, Animal, Preta, and Naraka. Each of these Paths, or realms, represents one of the realms a being is reborn into after death, determined by the accumulated karma of their past lives. While the two lower Paths, Preta and Naraka, are hellish, and the two higher Paths, Deva and Asura, are heavenly, all six are considered to be Paths of suffering because they perpetuate the cycle of Reincarnation; the only way to break it and ascend to a higher state of existence is to attain enlightenment.

Trivia

 * Despite Nagato being a sensor, none of the Six Paths he created seemed to share this ability; even the Deva Path, which was the only Path through whom Nagato used techniques unrelated to its abilities.
 * All of Nagato's Six Paths of Pain, except the second Animal Path, had interacted with Jiraiya during his journey, while they were still alive.
 * All of Nagato's Six Paths of Pain had the same hair colour as Yahiko, except for his Asura Path, which was bald.
 * In the anime, Nagato's original Six Paths all spoke in Yahiko's voice, although each of them had voices of their own in life. Nagato's second Animal Path, however, spoke with its own voice.
 * Three of Nagato's Six Paths of Pain are playable in Naruto Shippūden: Ultimate Ninja Heroes 3, while the other three appear as support characters. All six are able to appear simultaneously in three-versus-one match-ups. The playable ones are Deva, Asura and Animal, the ones whose primary function is battle, rather than support.