Michael is an archangel who serves as one of the primary antagonists in the series. He is a divine being with an ancient origin, yet his appearance is that of a youthful, cherub-like figure with short white hair and yellow eyes. He wears armor and a cape, signifying his status as a warrior of heaven. His role in the story begins when he descends from heaven to confront Maria, the powerful witch who has been using her magic to interfere in the Hundred Years' War. Michael views her actions as a violation of the natural order, insisting that humans must resolve their own conflicts without divine or magical intervention. After a direct confrontation, he decrees that Maria will lose all her magical powers if she loses her virginity, and he forbids her from using magic in public. To enforce this, he sends the angel Ezekiel to watch over her.

Michael's personality is initially stern, authoritative, and uncompromising. He is deeply committed to the laws of heaven and believes that Maria's interference in human affairs is unacceptable. He does not hesitate to impose harsh consequences on those who defy the divine will. However, as the story progresses, his rigid stance begins to soften. When Maria is brought before him for execution after using magic to save Joseph, Michael is confronted by the pleas of her friends and fellow witches. Rather than simply condemning her, he uses his power to gather the opinions of everyone who has known Maria. This act reflects his ability to listen and reconsider, suggesting a capacity for fairness and mercy beneath his severe exterior. In the end, he spares Maria and instead judges Ezekiel for siding with her, decreeing that the angel will be reborn as a human.

Michael's motivations are rooted in maintaining heavenly order and preventing mortals from disrupting the delicate balance between heaven and earth. He sees Maria not as evil, but as a disruptive force that must be controlled. His key relationships include his role as a superior to Ezekiel, whom he tasks with overseeing Maria, and his adversarial dynamic with Maria herself, which evolves into a grudging respect. He also interacts with other witches, such as Viv and Edwina, who defend Maria. Michael's development is marked by a shift from strict judgment to a more nuanced understanding of love and human choice, culminating in his decision to let Maria live.

Among his notable abilities, Michael possesses immense divine power befitting an archangel. He can confront and overpower magical beings, deliver decrees that alter the very nature of a witch's magic, and summon the testimony of others through supernatural means. His authority is absolute within the celestial hierarchy, and his presence commands fear and reverence. Despite his initial antagonism, Michael ultimately demonstrates that even a heavenly being can be moved by the strength of human bonds and love.