Wonder y it never shows his ems? Whey time kakashi uses his teleport jutsu he show his ms, but y not tobi?
It seems that while Kakashi requires his MS to do Kamui (his teleport jutsu), its apart of Madara's basic sharingan ability. If that's the case, then the question is, what is EMS ability then

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But back to topic, I think its apart of his aesthetic and him keeping incognito. Everyone keeps saying he's hiding his face because he doesn't want anyone to know that he's not really Madara. I feel its the complete opposite; He didn't want his enemies know that he IS Madara. Remember when he fought Konan (manga spoiler) he basically said he wanted people to think he was dead. It also conceals the fact that he has a Sharingan.