Kuromajo lulu

She is a ghost of the Spirit World and a Black Witch. However, she cheated in becoming a Black Witch by offering human sacrifices one every month. She posed as a transfer student to take Ero-Ace as the sacriface. However, this was thwarted by Choco and Gyubid. In episode 31, Gyubid accidentally summoned her when playing magic world shitori. Lulu's reason of becoming a black witch is to not be alone and make friends.