Seeing the Happy Sex tag on this makes me laugh. I mean, it's obviously true judging by her expression. Just not the kind of situation I expect to see that tag apply.
Nyx is just a complete slut. She can't do anything without the staff and she depends on it so much. I don't think she even has any relationship with any other characters in Queen's Blades, except Elina. She was solely created for tentacle rape.