Etna is the leader of an all purpose Prinny squad she hired, and one of the few vassals who remain in the Overlord's Castle after King Krichevskoy's death. In the beginning, she attempts to wake up Laharl through "unique" methods (from drills and flails to gatling guns, swords, and jackhammers). From then on, Etna becomes Laharl's closest vassal, though not necessarily most trustworthy vassal, aiding him in his rise to power. She is the only vassal from Laharl's original servants who goes out on the battlefield for him.

Etna acts carefree, but is also very devious. Often it is hard to tell for whom she really is working. She holds deep respect and loyalty towards King Krichevskoy, Laharl's father. Etna is often known for ending an episode with an odd "preview" to the next episode, all of which have her in the starring role. Often these previews parody famous TV shows, anime, or video games with the other characters making side comments. She also has a furious temper sometimes, especially when someone tries to eat her snacks in her stash, or when the Prinny squad is not listening to her: even Laharl has to yield to her temper at times.

In all but the "Flonne Tragedy", "Good", and "Human Conqueror" ending, Laharl gives up his position as Overlord to Etna. In one ending, she even murders Laharl and Flonne to get the throne, while in the anime, she is given the position of Overlord after Laharl decides to sacrifice his life for Flonne.

In the PSP and Nintendo DS ports of Disgaea: Hour of Darkness, there is an alternate mode in the game called Etna Mode. In this mode, rather than awakening Laharl, Etna accidentally kills him and sets out to become Beauty Queen Ultimate Overlord Etna. Etna mode gives the player a closer look at Etna's past, showing how she was taken in by Krichevskoy. At the end of "Etna Mode" in the PSP and DS remakes of Disgaea: Hour of Darkness, it is subtly hinted that Etna may have some form of affection for Laharl (She was seen deeply regreting her betrayal and crying to herself over her killing of the prince, and offering him a small prayer for his "peace and eternal rest".)