If UFC wanted to be in Japan already, they would be. There's no hurry to get there anymore. The Japanese have shown disinterest in MMA. Sengoku is in trouble, Dream is about to fold and cant get any decent ratings, etc. It really isnt that important of a market anymore. And this isnt a first to market situation. There isnt any need to get a toehold on the market as it has been oversaturated in Japan and is declining, not growing. China would be a whole different story.
And what a surprised - Overeem and Barnett are fighting in Japan where theres no testing
.