Buried in the ground, long forgotten, is a strange artifact known only as the Monster Girl Cube. This cube contains a powerful curse, and was sealed away because of it. Those who come into contact with it, male or female, were said to have transformed into sexy monster girls. These victims were forced to serve the cube, submitting completely to it's will. No one knew where this cube came from, what it's purpose was, or even if it's alive. The legends say that after a long war, a race of wizards buried it inside a magical chamber in a hidden temple.
Now it lies in wait, but not for too much longer, as our protagonist is about to dig it up. Who knows if they know what they are getting themselves into, but soon, the cube will be released from it's prison, and unleash it's curse upon this world yet again.