I read this doujin really long ago,
There was this merchant or shop owner or something he or his boy was doing something in street where a carriage nearly runs over him but saved the boy then it turned out to be it was a royal carriage which had a fat female princess inside who blames everything on this man/merchant and he was held responsible and kept as prisoner/toy of princess away from his family which consisted of wife and daughter, the wife also fell victim to the princess and an ugly looking man rapes her daily and later his daughter also when this whole cycle of breaking there minds ends the new carriage of princess does it again and doujin ends there
This one has to be one of the best I've read.