There's a rudimentary battle system that lets you fight alongside (or against!) the many lovely ladies Saito runs into. There's also the so-called "Tsun-Dere System" that visibly tracks how Louise feels about Saito. Stay honest and rebuke the other ladies' advances, and she'll be happy and let you know it; make her feel like you'll hook up with anyone of the opposite gender, and she'll beat you into submission. Of course, if you keep things balanced then you can have your cake and eat it too -- after all, this is a fantasy, right?
This limited edition includes a pair of drama CDs, "The Master's Tsundere Disc" and "The Master and the Familiar's Secret Diary Disc".