If you haven't found the succubus tower, there is a secret passage to the left at the start inside transylvania. Go pass the inn then go to the wall at the left and pass through head to the tower and rinny will be on the first floor
rinny is in the forest iirc you gotta help free her from fairies
Edit: wait I'm dumb LMAO you probs mean where she is in Transylvania, she's at the succubus tower, it took me awhile to figure out how to get there too, I think it's the left when you first enter Transylvania? There's a fake wall you can go through