First off, I like this game so much - it's sexy, sometimes creepy, and consensual. Nicely done! Suggestions reflect enthusiasm for a cool game.
A few ideas to improve the gameplay (in priority order):
1. An button to skip the town visit and have the night pass, possibly for a droplet boost. Sometime you want to leave the people alone as you modify concubines and beasts.
2. Score mode: A quick fix to the end game is that you can't beat the baron; his forces get stronger and eventually overrun you. The succubus could then move to a new lair, and the number of turns you lasted are a high score. Possibly you get to keep some of the mods on the succubus. This gives both a measure of accomplishment and a reason to re-play.
2b. (not a quick fix) expand the intriguing lore of the meta game - the Baron is coming for you, but so are the other organizations. Some of your own minions have returned topside. Feels like there's a plot that could be exposed.
3. Your minions get hurt in battle...but it doesn't seem to matter. Should they need to recover (lose turns) or lose enhancements?
4. Displaying information about the location of the lair at the top of the screen consumes real estate, once you have read it once.
5. It would be nice if the diary listed minions that left, died, etc. (at the bottom), record of attacks, etc. so it's a reminder of what happened.