Mata Hari

Mata Hari, whose real name is Margaretha (マルガレータ, Marugarēta), is one of the Witches invited to Walpurgis. She holds the title of the "Witch of Secrecy" (『密』の魔女, "Mitsu" no Majo), and her desire is unknown. She also serves as the leader of The Witches' Hammer.