Board Thread:Naruto Discussions/@comment-142748-20150403221647/@comment-4271790-20150403223458

SuperSaiyaMan wrote: The Rinnegan is only awakened via the combination of Asura and Indra's chakra. It was stated that Hagoromo's chakra awakens the Rinnegan in chapter 671, page 5. It explained there that Indra and Asura's chakra had to mix to become Hagoromo's, then, the Sharingan became the Rinnegan. Hence, how Sasuke got the Rinnegan without gaining Asura's chakra.