There seem to be a lot of people under the impression that he is not or is some kind of NORMAL HUMAN. His title in the original trilogy is "Mechanized Space Ninja".  Further proof is that the Soul Calibur version of Yoshimitsu speaks Japanese and is thus human while the tekken version speaks alien gibberish like Ogre does. He became more mechanized as the games went on and in tekken 1 and 2 the face is human like but not human. He was always meant to be a mash-up like a ninja pirate zombie robot.

Thank God. I can finally sleep.

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I think I'm having a revelation!

He's wearing a mask, and the arm is artificial because it sliced off.

I haven't playing Tekken in such a long long time, but, I seem to remember the Tekken speaking japanese, although hard to understand.

geez... don't react like an ass... Many Bothans died to bring Trentonator this information...

hE SPEAKS gibberish in tekken  that only sounds japanese. Japanese players know this.