Disgaea 4: A Promise Unforgotten

Valvatorez, a vampire who was once feared as a tyrant until he promised a woman 400 years ago that he would not drink blood until he could instill fear in her, and she died before he could do so. He now has a menial job in Hades, where the souls of dead humans are sent to be transformed into Prinnies. When the Corrupternment orders the mass extermination of all Prinnies, Valvatorez and Fenrich put a stop to it and, disgusted by the government's actions, Valvatorez plots a rebellion. (wikipedia)