Board Thread:Theories and Speculation/@comment-1512913-20161125200227/@comment-734582-20161128200849

Elveonora wrote: What do you think about my power splitting in different ways theory? Red Rinnegan and purple Sharingan? Well considering both had Byakugan, i think it's as close to fact as we can get here.

So yes, Momoshiki's rinnegan is probably red because the power split is artificial, unlike the natural splitting of power we saw with Hagoromo and Ashura/indra.