Kaibutsu Oujo S01E20 - Princess Connection

After Hiro visits Sherwood, Riza finds him on the road to the mansion. All of a sudden, a vampire named Duke Dracul soon defeats Riza and kidnaps Hiro. Hime orders Riza and Reiri to go and fetch Hiro from the Dracul's castle. Making it to the vampire village, Riza allows Reiri to suck her blood to become a temporary vampire. When the two approach the castle, they are attacked by a cyclops guard. They manage to push it off of the tower into the moat. Hime and Flandre arrive with the mermen and cause Dracul to retreat. Riza and Reiri then save Hiro.