Hime Dorei: Mesu e to Ochiyuku Futago no Oujo(2008)

Princess Tita is the successor to the throne of the Ruvens Kingdom. Tita's sister Liese hired Waldo, a practitioner of black magic to make sure that Tita doesn't rise to power. Waldo has but one condition upon accepting the request: the method is up to his choosing. (OVA Based on a game by Bishop.)