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 )

Pixy's adaptation of Taimanin Murasaki (or Hell Knight Ingrid), the third Taimanin Asagi game by Black Lilith. 
Said to share the same animators as those who worked on Aniyome wa Ijippari.

Ziz's adaptation of Taimanin Murasaki (or Hell Knight Ingrid), the third Taimanin Asagi game by Black Lilith. 
 
Ingrid, a once feared and powerful Knight has fallen into the hands of a madman who has enslaved her body and mind. Forced to do the sexual bidding of her master with no ability to fight back she is broken and raped endlessly. 
 
(Source: hanime.tv)