This looks rather interesting but if you don't mind I could use some more information.

Firstly exactly how did all six come to lose there memories?
Some more information on the world would be helpful regarding cities, social norms, social classes and other such relevant information on the civilizations involved, you know general knowledge for someone in the world.

Lastly any more information on the power structure would be helpful including where the Marquess and his children fit into the ruling class and any details on where he lives or might have been when the assassination took place.