ゼロ, Doro Yami no Majo (泥闇の魔女)
The title character. She is a witch childlike in appearance but presumably much older. She is proficient in both Sorcery and Magic having developed the latter. Despite her immense knowledge she is clueless with regards to basic knowledge such as the value of gems and monetary transactions. Situations that may normally embarrass others hold no problem for her. She employed Mercenary after promising to grant him his true human form.