Board Thread:Theories and Speculation/@comment-1512913-20161119171442/@comment-25122992-20161207224610

Well, I think BeyondRed stated a plenty of reasons why Susanoo without MS/any eyes at all is pretty weird. MS may be a manifestation of special chakra from the brain, but it seems to play a separate role in casting MS techniques after it got awakened through this chakra. I mean, it's something akin to a conduct that allows this special chakra to manifest as a technique and take effect, and since individual MS techniques are surely utilised via chakra concentration in one of the eyes, no such a technique can be used without the MS eye itself. I don't know if this principle applies to Susanoo, but Sasuke's and initially Madara's use imply that it's really so, since they always had to activate MS in order to summon Susanoo. Without any eyes at all, Madara should've lacked this "conduct" to manifest Susanoo.

Also, there's still the problem that non-Uchiha can also use MS techniques through a transplantated eye, despite the fact their brain cannot produce the special chakra of Uchiha and thus power the MS techniques, unless the eye itself always keeps this special chakra within itself and can constantly generate it. Yet another question raises there: why then do the MS jutsu rapidly consume the user's chakra even if they aren't Uchiha and thus don't produce this special chakra while only the eye itself does? With this question, I got an idea that the brain produces this special "MS" chakra only once to give the special properties to the eyes themselves, and MS techniques are already used with a regular chakra, yet only the eyes can be a "conduct" that is able to give this chakra a proper form and manifestation as an MS technique.

In any event, there are two facts that contradict this logic: Madara's eyeless Susanoo, again, and Kakashi's awakening of MS despite lacking special Uchiha chakra from the brain.