Yahiko

was a shinobi from Amegakure; his body acts as the Deva path of Nagato's Six Paths of Pain.

Background
Yahiko was orphaned during the Second Great Shinobi World War and thus he started fending for himself, stealing food from others. He later encountered Konan, also an orphan, and the two began to work together to survive. After this, Konan brought another orphan, Nagato, and his dog, Chibi, into the group. At first, Yahiko was upset that she was bringing more people but he accepted Nagato and Chibi into his gang. Angered by how unfair the world was to them, Yahiko declared he would become a god to end the fighting.

The three eventually encountered Jiraiya, who looked after them and taught them basic ninjutsu. At one point, Nagato saved Yahiko after an Iwagakure Chunin. Afterwards, Yahiko vowed to become strong enough to protect Konan, Nagato, and eventually all of Amegakure.

Sometime after Jiraiya's departure from Amegakure, the three gained a reputation as a talented shinobi team. Still desiring to create a world of peace, Yahiko and his friends went on to become full-fledged Ame ninjas and gathered many supporters who shared their hope for a better world. Together, they began spreading their beliefs to stop war without violence. Unfortunately, the current leader of Amegakure, Hanzo, viewed Yahiko and his supporters as a threat to his power. Working with Danzo, they captured Konan and forced Nagato to choose between saving Konan or killing Yahiko. Without hesitation, Yahiko ran into a kunai that Nagato was holding. With his final breath, he told Nagato, their savior, to continue their mission of finding peace.

Deva path
Nagato, using his Rinnegan and chakra receivers, incorporated Yahiko's body into his Six Paths of Pain jutsu. As the Deva path, Yahiko's body has acted as Pain's main body, it being the one he most commonly uses and speaks through. The Deva path is held in higher regard during combat, some of the other bodies being sacrificed to ensure its survival. Following the Deva path's defeat and Nagato's death, Konan takes both of their bodies back to Amegakure.

Personality
Yahiko's personality was similar to Naruto's. His dream was to be a leader of his village and he never gave up no matter what. When he was alive Yahiko had a strong "eye for an eye" philosophy. He hated the way Amegakure was looked at by the rest of the world and hated what it had become. He was defensive of the village, saying that was his dream to stop the endless rain, which he compared to tears, and protect the nation's citizens. Yahiko wanted to become the ruler of the world so there wouldn't be any wars. Many of these traits are adopted by Nagato after Yahiko's death.

Among the three Ame Orphans, Yahiko seemed to act as the leader of the group. It was Yahiko who first approached the Sannin to ask for food, and the first to ask Jiraiya to teach them ninjutsu. He also seemed to act as an older brother for Nagato, reminding him to not cry and act more manly. He also wished to become stronger so as to protect Nagato and Konan.

Abilities
Yahiko had the ability to use water-based jutsu, though the only example of this seen in the series is Water Release: Violent Water Wave, in which he was able to shoot a jet of water from his mouth. The Deva path also had the ability to control rain, presumably Nagato fulfilling Yahiko's desire of "stopping the endless tears".

Trivia

 * Yahiko shares his birthday and blood type with his former teammate, Konan.