Plaintive Betrayal Shinmai Maou no Testament : Season 1 Episode 10

Mio has been captured by Zolgia following Maria's betrayal. Basara too is captured by Lars and brought to Zolgia's mansion. Lars' goal is to exchange Basara for Mio. He explains that he's only doing his duty as Mio's observer, but negotiations fail, and Zest slays him.