Miho Karasuma is a nineteen-year-old hunter and craft user working for the STN-J, the Japanese branch of the Solomon organization. Her primary ability is psychometry, also referred to as scrying, which allows her to read the lingering emotions, thoughts, and even past events tied to an object simply by touching it. This power is limited to inanimate items, making her an invaluable asset for investigating crime scenes and examining evidence, as she can uncover clues that no ordinary method could reveal. Despite her young age, Karasuma carries herself with a serious, professional demeanor and is deeply committed to her work. She dislikes trivialities and distractions, and she approaches each mission with a logical, methodical mindset. Her strong sense of duty and attention to detail make her a reliable member of the team, though she can appear reserved and guarded, likely due to a troubled past involving witchcraft that she does not openly discuss.

As the second-in-command of the STN-J, Karasuma often operates alongside Amon, the team's lead hunter, and shares a professional rapport with him. When Robin Sena, a new hunter with pyrokinetic powers, joins the team, Karasuma becomes her mentor. Because both are craft users, Karasuma offers Robin practical advice on how to better control her abilities and navigate the challenges of hunting witches. Over the course of the series, the two develop a close friendship, with Karasuma acting as a supportive figure for the younger hunter.

Karasuma's role in the story centers on her investigative contributions and her steady presence within the team. She is highly motivated by a desire to protect society from dangerous witches and to carry out her duties effectively. As the series progresses, she undergoes notable development. After Amon disappears, she steps up to become the new team leader. In this role, she becomes intensely focused on continuing his work, sometimes even taking unnecessary risks in her determination to live up to his legacy. This obsession reflects her deep commitment to the mission, though it also reveals a vulnerability beneath her composed exterior. Ultimately, Karasuma's journey highlights her growth from a capable second-in-command into a decisive leader who willingly shoulders greater responsibility for the sake of the team's goals.