Nightmare Fortress: Majin no Jousai

There is a kingdom on a island somewhere in the four seas. All was well until one day it was attacked by an army of Demons via Sodomy - and of course the Prince of this kingdom was taken prisoner by the Devil King. With his last strength, the Prince casts a spell that takes this island to another realm, making it invisible - so that this "carnage" is maintained. Our main two characters are the Princes #1 bodyguard, and the bodyguard's protégé - so thus begins their quest to regain the kingdom, kill the demons, and save the Prince. But it won't be that easy, cause watch out the Demons are always ready for a thorough tumble!