Ingrid was a member of a secret organization of humans that was allied with the demons. She was known as the Dark Knight. Under the command of Edwin Black, Ingrid was assigned to capture the Anti-Demon Ninja Murasaki Yatsu. Though, the scientist Kiryu had revealed he already abducted her. She had already suspected Kiryu to be a traitor and was just using his Black's organization to fulfill his vengeance. Ingrid is lovely and stern demon-hunter who fights under the command of Edwin Black in the Demon City Tokyo. ( source animevice )