Mullin

A young male demon with blue hair and blue eyes, he is Beelzebub's Head Attendant and prefers all work to run smoothly and efficiently. He has some Tsundere characteristics with other demons claiming he has the "pure heart of a maiden." He is easily embarrassed and will blush whenever he is exposed to Beelzebub's naked body or anything to do with sex. He is often frustrated by Beelzebub's behaviour and while he respects her leadership skills he is more than willing to scold her ditzy airheaded behaviour. He is strongly attracted to her and often cannot handle how cute she is. He is highly protective of her and has at least some ability to fight as he quickly dealt with two thugs harassing Beelzebub when she was lost in the city.

(Source: Wikipedia)