Gate of Nightmares occurs in the mystical lands of Wistaria and Remulias, where sorcery and blades reign supreme and people's dreams take physical form. Emma, a young woman transformed into a "Nightwalker," who commands a horde of evil dream creatures known as "Nightmares," serendipitously meets Azel - an enigmatic boy that the Nightmares surprisingly have an unusual fondness for.