Why do you suppose that EJ? I'd have thought Raonic is the favourite depsite home support and him having a much easier match today than Raonic did. I hope Nishikori does win as I like him and it would be great for him and Japan but I'm not expecting him to.
Just assessing the situation at hand. Raonic had two very tough rounds against Tipsy and Andy. Both went to final sets and he even faced a match point against Tipsy in the qtr and against Andy, that too came down to 2 points in the TB. Nishikori, on the other hand, destroyed Berdych in straight sets and yesterday's match was even easier than the previous round, so he should be relatively fresh and ready. This is his home country so that should play a part as well. They have never played before so I think it will be more tricky for Raonic than Nishi given all that.
Also, Raonic gave his all against Andy last night so I don't feel he'll be able to bring the same level and consistency in the final match against a tricky player like Nishikori, who I believe can handle big servers. He will just have to be very patient and wait for his opportunities. Also, Nishi too has experience playing big matches so that's another bonus. Let's see though.