Chikara Oosaka

Ten years after the Great War against the demon-beasts, the empire rules over the world and prosperity relies on the massive use of aer. Yuri Lowell and Flynn Scifo are two young men who have just enrolled the ranks of the prestigious Imperial Knights. One day, they are sent to the town of Ceazontania, where abnormal aer activity has reportedly caused the proliferation of horribly mutated beasts, with serious threat for the whole region.

Roberta, the terrorist-turned-maid that made her appearence in the first season of Black Lagoon, returns in this five-episode OVA series-and this time, all bets are off! Roberta's benefactor, the patriarch of the Lovelace clan, is murdered during a political rally. The assassin's trail soon leads back to Roanapur-so now she has returned on a mission of vengeance! However, close behind her is the new patriarch, Garcia, as well as Roberta's apprentice (and maid), Fabiola Iglesias. (myanimelist.net)