Isabela

Riser's Rook. A woman who wears a mask on the right side of her face. She was incapacitated by Issei's Dress Break before being defeated by Issei's Dragon Shot. Unlike Karlamine, she considers honor to be fulfilling Riser's wishes by any means necessary and fair play optional. She reappears in Volume 5 as Ravel's escort during the Young Devils Gathering.

(Source: Wikipedia)