Makai Senki Disgaea MangaDisgaea, Disgaea ~Battle Chronicles of the Netherworld
So... you wake up one day after a two-year nap and discover that your father is dead. What do you do? Take over his kingdom and rule with an iron fist, of course! Laharl may be new to the whole Overlord scene, but with the help of the demon-girl Etna and the angel-ditz Flonne, he's going to be the best ruler the Netherworld has ever seen. All he has to do is get by the hordes of halfwit hellions determined to challenge him for the throne, foil an interdimensional plot, and keep his own vassals from trying to kill him. Sound rough? Hell yeah.