Kind of hard to answer with out giving out spoilers. Yes, there is some breast growth. One of the complaints most often heard is that the girls have large breasts. And by large, I mean 2 or 3 cup sizes bigger than what I suppose is considered 'normal'.
If you like big boobs, you'll probably enjoy the game or at the very least the artwork. You should know within the first 10 minutes of game play. If you have downloaded the game, double check that you have also download the additional bugfix. It kind of easy to miss, but the link is on the first page of the thread.
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My only other suggestions is to download and read the Companion Guide, also linked on the first page of the thread.
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