Six Paths of Pain

The Six Paths of Pain is a technique used by Nagato, and served as his representation in Akatsuki. It allowed Nagato to control six separate bodies as though they were his own. Each of these bodies were reanimated corpses which were both kept mobile by, and made use of, Nagato's chakra. While controlling them, Nagato used the alias "Pain", yet still regarded them as separate from himself. All the six Paths were eventually destroyed by Naruto Uzumaki during the Invasion of Pain.

Nagato
In order to use the technique, Nagato remained in a large, chair-like machine that moved with six relatively short mechanical legs, and used several large chakra rods protruding from his back to transmit chakra. From there, his chakra was picked up by the numerous body piercings that each body possessed, which acted as chakra receivers. However, to control them, Nagato had to be ideally at the highest and closest point possible so that he could have the best range possible. Inoichi Yamanaka compared the ability to the Yamanaka clan's unique Mind Body Switch Technique, albeit on a greater scale.

Paths
As the name suggested, there were six bodies, or "paths", which comprised the technique. The only common feature shared by these bodies was their bright orange hair and Rinnegan. Each path had a number of body and facial piercings of various shapes, sizes, and patterns. Also, 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. 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 center, 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" on which the bodies rest; 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 faces of the inactive body. The pods are also numbered from one through six using daiji characters, and are ordered counter-clockwise around the room as follows: 壱 (1) - Deva Path; 弐 (2) - Asura Path; 参 (3) - Human Path; 四 (4) - Animal Path; 五 (5) - Preta Path; 六 (6) - Naraka Path. This numbering scheme corresponds with the ordering of the six Buddhist paths of Reincarnation.

Madara Uchiha
During the Fourth Shinobi World War, Madara creates his own version of this technique, using the six revived jinchūriki. He also customised them, giving them each a Sharingan as well as a Rinnegan; mirroring his own eyes.

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

 * Among Nagato's Six Paths, the only two bodies who have not had their hair colour altered are the Deva Path which retains Yahiko's natural hair colour and the Asura Path which was bald.
 * Three of Nagato's six paths of Pain are playable in Naruto Shippūden: Ultimate Ninja Heroes 3, while the other three will appear as support characters. All six will be 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.
 * 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.
 * As noted by Konan during Chapter 430, Nagato's technique output is considerably more powerful when he focuses on the Deva Path, however this is considerably risky as the other Pains are slow to recover.
 * In the anime, Nagato has all six paths (except the second female Animal Path) possess Yahiko's voice.