Etna is a recurring character in the Disgaea series, She is a manipulative demon intent on gaining power, and also hides dark secrets within her heart.

In Cursed Memories Etna quits her position as Laharl's vassal after a fight with Laharl over pudding (which is supposedly a rare delicacy from the Sea of Gehenna) and becomes a Demon Lord, taking the Prinny Squad with her. She then travels to Veldime, hoping to eliminateOverlord Zenon, the God of All Overlords.

In Episode 9, she gives Adell a fake "Demon Lord's Nail" and is accidentally summoned by his mother. The failed summon drops her back to level one, and in order to regain her former power she decides to join up with the player's party. At the end of the game, she, along with Hanako, returns to the Overlord's Castle as Laharl's vassal once again.

" http://disgaea.wikia.com/wiki/Etna "

I've realized also the artbook version with Flonne -