Ullr acts as a covert assistant to Kikko Hoshino, hidden beneath her clothing while whispering guidance to her and other sorcerers. This discreet entity knows Kikko’s true identity as an inter-dimensional demon whose powers arise from indirect contracts with rescued individuals. Kikko’s demonic heritage marked her as a candidate for queen of the demon realm, leading to her dispatch to the human world to find a husband. Ullr later reveals that Kikko’s emotional attachments and diminished powers void her demon queen eligibility. Resembling a round, stylized Daruma doll, Ullr stays concealed from anyone beyond Kikko’s inner circle, maintaining absolute secrecy. During Kikko’s magical girl transformations, Ullr’s star-shaped ornament integrates into her staff. In Kikko’s devil realm form, she wields the weapon "Comet Tail," seemingly manifesting from Ullr’s star component.