I have updated recently, and I'm getting a new version of this problem. After I meet the guy in the tower, the whole game locks, and says there is no more content, when in a previous version I could get slightly further along before it crashed.
Viewing post in Hom Factory : My Monster Girl Tower comments
Android build has always had issues after a certain point.
I've tried to pin these down, but it really seems like a phantom bug associated with the build process.
As such, I've stopped updating android versions of the game. Instead, you can use Joi Play to play on mobile.
Check out the latest release post (or the main page of the game) for instructions on how to set up Joi Play.