Frey is a Harpy with wings on her back and talons as feet, although she can hide her talons to have human-like legs in place. She has white hair, gold-brown eyes and usually wears a sexy red dress that emphasizes her large chest. 
She's careful, cunning, friendly, kind, with a maternal instinct towards Milim and, despite her former title as Demon Lord, never arrogant, but instead very humble. She is also kind and friendly with Milim, showing a maternal side and deeply caring for her.