Sage of the Six Paths - Rikudo Sennin

The Sage of the Six Paths, Rikudo Sennin was a legendary god-like figure who founded the arts of ninjutsu and created the ninja world. He defeated the Ten-Tails in battle and sealed the beast within his own body, thus becoming the very first jinchuriki.

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The Sage of the Six Paths was a man who sought peace by spreading his wisdom across the world. He was exceptionally wise, as he was able to bring about a great change to the world by simply disseminating the principles of chakra and his religion. He also seemed to care a great deal for the tailed beasts when they were still with him; he gave them each a name as a sign of their individuality, and told them that no matter how far apart they grew, they would always be together, and would someday be led down the right path. In return, the tailed beasts showed respect and adoration for the Sage. Kurama even shed a tear at the thought of his imminent passing, suggesting that the beasts might even have viewed him as a sort of father-figure.
 
Though not a great deal is known about all the skills the Sage possessed, he is widely accepted to be the most powerful shinobi of all time, having been the only person to defeat the Ten-Tails: a being that was revered as a god, causing the Sage himself to be seen as a god. The Sage was also revered as the man to first understand the very nature of chakra itself. This wisdom, combined with his kekkei genkai, the Rinnegan, allowed the Sage to create the first modern ninjutsu.
With such powers at his disposal, the Sage obtained a great following, as men and women from across the world strove to learn from his teachings. As the Sage's disciples grew continuously greater in number, it led to the creation of ninja clans, and later, ninja villages.

It is impossible to overestimate the Sage's effect on the course of the ninja world's development. As the first true ninja, he created the ninja world, revolutionised it, and left it forever changed. The Sage was shown carrying two objects. One was what appeared to be a katana in his hand, whilst the other was a shakujo � a Buddhist ringed staff which is meant to be used in prayer. As time passed, the Sage ultimately faded into legend. His bloodline was divided into the descendants of his two children, which would eventually form the Senju clan � and through distant relations the Uzumaki clan � and the Uchiha clan.

As a result of Madara Uchiha acquiring and integrating Senju DNA into his body, the Rinnegan would later resurface. Though he noted nothing happened initially after the DNA integration, when he neared the end of his natural lifespan, the dojutsu finally awakened. With that, Madara Uchiha managed to undo the Sage's seal on the vessel of the Ten-Tails by summoning it from the moon and formulated the Eye of the Moon Plan to become the Ten-Tails' new jinchuriki.