Pretty standard stuff. Girls go in and don't come out. Amputation fetish. The guy from the most affluent bloodline in the area has suitors lined up because the other families want to marry into money. Such is the cold cynicism of the world.
This is true ero guro manga, not comedy like Hentai Shounen. The art is mediocre, but the storytelling is nice and dark. It's a refreshing break from the more conservative manga about death games and haunted houses. This one goes whole hog, with girls losing body parts and becoming permanent residents of the mansion. Give it a read.