Disgaea

Flonne, an angel assassin-in-training, is supposed to eliminate the demon Overlord but ends up awakening Laharl, the demon lord and heir to the throne, instead. Laharl, accompanied by Etna and her penguin-costumed minions, aims to restore order to the Netherworld after it falls into chaos. Based on the events of Disgaea: Hour of Darkness, their journey involves squashing a demon rebellion, reclaiming the throne, and deciding whether to let potential allies join them or thwart their progress.