Board Thread:Theories and Speculation/@comment-1512913-20161119171442/@comment-734582-20161204165735

Ravenlot 27 wrote: Technically, the eyes don't even seem to be the source of Susanoo. Considering that Madara used it without eyes, i'd say that's confirmed.

Elveonora wrote: Hm. I'm 99% sure that Susanoo uses Sharingan chakra, the same 'special uchiha brain chakra' as Sharingan does, but you don't really need eyes for it once you already can use it, the chakra is in the brain, doesn't need to go to the eyes to use Susanoo. According to Tobirama, the brain is the real source of the sharingan. It creates the chakra that transforms the eye. It makes sense that this same chakra also modifies the brain to allow Susanoo to manifest.

So what is it about the Mangekyou that Susanoo requires? Does this requirement even exist, or is it just us misinterpreting facts?