You can see the original artwork for this at FredArt.
ガールフエーズ = Girl Phase (literally "ga-ru fue-zu")

Piro speaks:
The Girl Phase cover is a spoof of a stereotype of an magical girl style anime. Short skirts? yes. Sorry for breathing.
and frankly, in a genre when excessive clevage and panty shots are the norm, i like to think that i have an abnormally DULL comic when it comes to issues of fanservice.