As Miss Beelzebub Likes It. - Season 1 Episode 3 Former Angel with Wings. / The Assistant, a Complete Sadist.

Beelzebub and Mullin run across someone Beelzebub seems to know. His name is Astaroth, and he's surrounded by adoring girls. He calls himself Beelzebub's older brother, and starts going off on how much he loves Beelzebub. However, Astaroth starts to wonder about Mullin, and goes to visit the two while they were working, leaving behind is own work. But then Astaroth's assistant, Sargatanas, comes to get him, and he seems pretty afraid of her.