Akumi

A mischievous muglox who is always causing trouble for Mirumo and his friends during the second season. She admires Dark and is the first to join him. After Dark is destroyed for good, she changes from her evil form, becomes Saori's muglox, and leaves with her for Germany. In the Murumoya sequel, she is the main villain. Her magic tool is a sitar.

(Source: Super Fan Mirumo)