Two things come to mind when watching the previews and reading the articles:
1. There is nothing mature about this release

Yes, the hair is down and the dress is a bit more plain than usual, but other than that it's not 'mature' at all. Mayu playing around with bunnies and singing about Jelly Beans has nothing to do with a mature image.
2. Remember that photo shoot a while ago with all the bunnies? Who was it that was terrified of them? I thought it was Mayu, but seeing her have fun this time it might have been Yuki after all...
I'm quite enjoying all the previews and such

Bring it on!