There's an entire Wikipedia article dedicated the The Great Muta's poison mist, and the meanings of the various colors. Though I always look way to far into these things, it brought to mind a portion from "The Unreal Story of Professional Wrestling," where an author of a book about the subject raised the point that with the exception of organized religion, we are a society that grew up with no real mythology, and that in a way, pro wrestling in its various forms embodies a modern day mythology. Couple that thought with the fact that Japan DOES have its own mythology as well as a significant public investment in Puroresu (pro wrestling), and you have yourself quite a character. I always thought that the great Muta character would make an excellent horror villian in a hybrid slashser/martial arts flick.
And in case you've never seen him in action, watch Muta get iggy on this poor motherfucker: