Background: Nazo was a secret apprentice of the Sage of Six Paths long ago when he was alive. The Sage was the only one who knew Ninjutsu back then, and Nazo had a lust for power, so he trained under him. Knowing that the Sage had some great power inside of him, plus his eyes, he couldn't help but ask what he had and if he could have the power also, but the Sage wouldn't tell and from that day forth felt evil chakra coming from Nazo. Nazo didn't notice it himself but he had come accustomed to the power that he was taught (all 5 elements and yin and yang release also), but he eventually got driven away in madness, killing those he came close to. Eventually the Sage stopped him, but couldn't bring himself to kill him, so he left him alone in a deserted location, but before he left he explained where he got his powers from, but then suddenly left, and the sage did not mention him hence forth.
Being given up on he went on his own, making new ninjutsu and getting stronger. However, once the Sage died Nazo took note, wondering what he could do to continue living. He knew he would be on the brink of death soon, seeing how his powerful teacher had just died, so he started to experiment on himself, trying to make himself immortal, and one day he had it. He figured out that the Biju were now 9 entities, due to the Sage sealing the Jubi into the moon and splitting the chakra into 9 halves. From this point on he used one of the jutsus the Sage taught him, and in secret collected black chakra. He collected it as the Biju let off access chakra and when the wars raged, as when people die they let out black chakra. His first current goal was to create Winged Beasts. They would be the counterpart of the Tailed Beasts, and they would also be stronger, but first he needed to make them from Black Chakra.
During his years he noted Madara Uchiha, the leader the Uchiha Clan, and Hashirama Senju, the leader of the Senju Clan, were rivals, decedents of the sons of the Sage were battling, he couldn't believe that his teachers decedents would be doing this, but he was glad, as they were occupied with each other as they tried to get the tailed beasts, he could do as he pleased. Especially during war he got a lot of chakra, from the corpses that remained on the battle field. During this time he joined the cult of Jashin, giving them the details of how to become immortal. When they preformed the experiments on each-other they noticed many of there men died from it, and said that Lord Jashin wouldn't accept them to be immortal, although only a few actually survived.
During his later years when Akatsuki formed he noted that he got more black chakra when they sealed a tailed beast. He only really payed attention to this because it took away the competition as far as having to get rid of the tailed beasts themselves, but more so over, when the biju were being extracted he noticed that they let off a lot of black chakra during the extraction. Also he noticed that when stronger ninjas die they give off more black chakra, so when the Akatsuki members died he gained more chakra from that. During this time he has also been picking up on new techniques that were recently created. (Like Chidori, Or Rikiri)
After the 4th Great Ninja War he got almost enough black chakra to complete his secret plans, although it wasn't quite enough. Soon after that war a kid named Naruto Uzumaki had brought peace to the world, and he only gained black chakra for whenever someone died of old age or the sort, so it took him about 600 years, but he finally completed them, and now he is ready to move on to faze two of his plan.
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