There seems to be some news on the development of Utawarerumono 2 on this website:
[link]Apparently, it's halfway done according to the translation (and even when you're viewing the page in its original language). The site also contains a reference to Dengeki, which is a magazine that deals with game releases (to my knowledge, anyway). The thing about it is that going off Leaf/Aquaplus' marketing strategy, after their main advertised game is released in March, perhaps we'll be seeing more news about the Utawa 2. Maybe even earlier, at this rate.
As of now though, we know nothing of the plot and it will probably be explained near the game's release, which I hope happens soon. But, knowing Leaf/Aquaplus, it'll probably end up being delayed for a while.
Here's to hoping!