Board Thread:Theories and Speculation/@comment-1872728-20160229033316/@comment-734582-20160320220709

Georgio722 wrote: You're right about them being the first to awaken it in the Warring States Period, but in total there are numerous Sharingan users, Mangekyo Sharingan users, and even Susanoo users. So it's not really that rare if you think about it. Nope there aren't. The Anime took liberties with the Mangekyou. The Manga doesn't show this at all.