Board Thread:Wiki Discussions/@comment-1512913-20140521221412

This topic relates to the whole doujutsu "issue" There's actually none. The Shinju, Kaguya, Madara and Sasuke's left eye are one and the same. The confusion stems from Hagoromo's statement about Kaguya's eyes. He actually said: "besides the Byakugan, she also had power of the Sharingan" he didn't say "her forehead eye was a Sharingan"

Now, as you may know, the Rinnegan is also Sharingan by extension. Using power of the Sharingan doesn't necessarily mean having the Sharingan alone and rule out having the Rinnegan also, since just like Sasuke has used Susanoo with his Rinnegan, so did Kaguya use "power of the Sharingan" (infinite tsukuyomi) with her Rinnegan and Byakugan.

Now lets look at what the canon says:
 * It's been stated multiple times that the Rinnegan came first, since it was split into Sharingan and Senju whatever.
 * The Shinju is the deity of Narutoverse, creation and destruction incarnate, the all in one etc. so it doesn't make sense for Hagoromo to have gotten something which the originator didn't have itself in the first place. With each generation after Kaguya, the descendants have gotten weaker.
 * Since the Rinnegan came first, the Shinju and Kaguya can't have the Sharingan without also having the Rinnegan

So I don't really get what the problem is. 