Although kept out of sight from the general public, Witches—individuals with supernatural powers—have always been present in human societies. They are neither numerous nor inherently evil, yet Witches can still cause disorder by misusing their powers for criminal purposes. Solving supernatural crimes falls outside the jurisdiction of standard authorities and is instead managed by the Solomon organization. After completing her training in Italy, Robin Sena transfers to Solomon's local Japanese branch, STNJ. As a Witch herself, she possesses powerful pyrokinetic abilities, which puts her at odds with STNJ's methods for dealing with rogue Witches. Specifically, Robin opposes the use of an elixir called Orbo, capable of weakening or even neutralizing a Witch's powers. To find her place within the organization, Robin must navigate Solomon's internal politics while also addressing the threat of hostile Witches—both of which appear dangerous for very different reasons.