Honestly, this is a bugfest...
Mage girl is completely bugged and no scene plays nor unlocks; maid girl does her BJ scene every single time you get close to the dungeon... Gargoyle and another girl also bug out and you recruit another in their stead...
Progression is quite clever, though. Once you gained affection with Pxies and Slimes you can get hefty amounts of crystals.
What's dumb, is the time it takes to level up the late girls, like Cupid or Succubus. You can only ever do half a level with them, if you're lucky enoughh to tame one...
Wasted potential, really. Too bad. They should've taken the time to squash the bugs.
Stupid bug for stupid easy game: if you get a Pixie (or whatever girl) at 30+ affection, you can choose her as a partner. Then you can 'sell' her infinitely to Succubus merchant. Infinite money and crystals from floor 1...