Yahiko

is a deceased ninja 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. He began life as a thief and even made himself a crude hideout from a cave. Later, he encountered Konan after the murdering of her parents, and the two began to work together to survive. After this, Konan brought another orphan, Nagato, and his dog, Chibi, with her. At first, Yahiko was upset she started 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, which ultimately inspired Nagato to follow the same path.

The three eventually encountered Jiraiya, who looked after them and taught them basic ninjutsu. At one point, Nagato saved Yahiko after a Stone Chunin injured him, and kill the shinobi in a berserk rage. 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 Rain ninja and gathered many supporters who shared their hope for a better world. Together, they began spreading their believes to stop war without violence. Unfortunately, the current leader of the Rain Village, Hanzo, viewed Yahiko and his supporters as a threat to his power. Working with Danzo, they captured Konan and forced Yahiko as leader of his team to make a decision: surrender his life or watch Konan die. Yahiko without hesitation forced Nagato's kunai into him saving his friends. Upon his final breath, he told Nagato to continue their mission as their savior. The trauma of his death drove Nagato to pursue Yahiko's dreams, as well as adopt a harsher view of life. Nagato, using his Rinnegan and chakra receivers, incorporated Yahiko's body into his Six Paths of Pain jutsu. Since then, Yahiko's corpse, now the Deva path, has served as Nagato's main body while using the technique. This body is held in higher regard by Nagato and protected to a greater degree than the other Paths while in combat.

Personality
Yahiko's personality was kind of like 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.

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.

Water Release
Yahiko had the ability to use water-based jutsu including Water Release: Violent Water Wave, in which he was able to shoot a jet of water from his mouth. His affinity for Water Release ninjutsu was presumably carried over by Nagato in the Deva path's ability to control rain.

Trivia

 * Yahiko died around the age of 25-30 since a dead body cannot age.
 * Yahiko shares his birthday with his former teammate Konan.
 * Despite being the leader of his gang, he saw Nagato as their savior.