Prologue
Long ago, there was a seventh realm, the Chakra Realm, among the six realms that were made, courtesy of the Elder Gods due to the One Being feeding off of them. But the One Being had one last wish, for there to be a seventh realm, and he did just that, right under the Elder Gods' noses. Raiden, the God of Thunder, and protector of Earthrealm, had found out of its existence, and told the Elder Gods and they used their power to hide it from the other realms along with its Kamidogu, that way, nobody could resurrect the One Being.
But Shinnok, the God of Death, wanted the realm for himself, because it was a near-exact copy of Earthrealm, and even he knew that Raiden wouldn't give it up easily, so he held a meeting asking for protection and possession of the realm. The Elder Gods reluctantly agreed, wanting to know what Shinnok was scheming. The Death God foresaw what would happen in this realm, so he gave a certain family of creatures a fraction of his power. Who was this family? I believe they were called the Otsutsuki Clan. In this family, a woman named Kaguya had two sons who possessed Shinnok's power, but it was less chaotic due to their pure hearts.
These two sons were Hagoromo and Hamura Otsutsuki, two of the best users of the Byakugan, Sharingan, and Rinnegan. They would soon seal away Kaguya because of her rampage in the lands of the soon to be superhumans. Hagoromo was the more powerful one, earning the title as the Sage of Six Paths, but he didn't take the role as leader of the clan as he wished to protect the planet while his brother protected the moon. Hagoromo had two sons who split the clan into two, then 3, one beginning the Senju clan that soon branched off into the Uzumaki clan, the other with the Uchiha clan. The boys were Ashura, the Senju successor, and Indra, the Uchiha prodigy. Shinnok sent Kaguya's "son", Black Zetsu to corrupt the Uchiha boy, simply because of his inheritance of the Sharingan that he desired to have.
The siblings' rivalry soon began when the decision of who Hagoromo's successor was being decided and when Ashura was chosen, Indra was agitated and murdered his two best friends, achieving the Mangekyō Sharingan and attempted to beat his brother, but ultimately failed and left the village. These two brothers would soon begin a whole reincarnation cycle I don't wanna go into detail on.
A few millennium later, two boys, Naruto Uzumaki and Sasuke Uchiha, reincarnations of Ashura and Indra, fight for the fate of the world, after the resurrected Kaguya was resealed by the two shinobi. Naruto won, at the cost of his right arm, sparing Sasuke, who had lost his left arm. But their battle was so great, it had taken the shield made by the Elder Gods down, revealing the realm to others.
Okay, the prologue is over. If you found it boring, well that's because it just began so just wait.