I only got around to watching the Kyou Kara Maou episode 60 preview today (I forgot about it yesterday!). This has given me much more information! Highlight for spoilers and speculation:
Now it seems like there was more than one reason for the Shinou to send the fourth box to Earth. It looks like he’s planned more training for Yuuri by sending Dr. Rodriguez to fight him. A new thought occurred to me today: what if the Shinou isn’t evil? What if he’s actually trying to piss Yuuri off enough with these tests and dangers and cruel tricks to finally go against the Shinou’s will? Maybe he’s tired of sitting around in the temple dictating for his country; maybe he (like Bob) wants to finally be able to rest. But he knows that his country is too dependent on him for him to just disappear on them…so he found the perfect Maou to set the country on a new course of independence, and is now just trying to get things to the point where there is no longer any need for the Shinou. Putting the Great Sage there, someone he doesn’t need to spoonfeed, would further that goal.
That would be cool ;> Although it seems kind of mean to do that to Murata, doesn’t it?