Вельзевул

The titular character of the series, a young girl with long blond hair and blue eyes. Beelzebub is a former Seraph and the current ruler of Pandemonium following the unexplained disappearance of Satan. While most demons look up to her for her skills as a capable and intelligent ruler in private she is a ditzy airhead who rules only because it is her job and loves anything fluffy, in fact her lifelong dream is to become one big ball of fluff. She enjoys teasing her Head Attendant, Mullin, and frequently embarrasses him for her own amusement.

She is in love with him after an incident where he protected her from thugs made her heart race, but as she has had no experience with men she as yet does not understand what her feelings are. (Source: Wikipedia)