Invisible

is a fairy who only shows herself to Deathpierce and acts as his informant.

Appearance
She is a very small fairy with angel-like wings. She appears to be nude, save for a pair of lacy stockings that cover her legs.

In the anime, she is a fully clothed, with a white dress and white stockings.

Personality
She is apparently very shy, only showing herself to Deathpierce and whispering to speak to him instead of speaking aloud, likely because she doesn't want anyone else to hear her.

Great Fight Festival arc
Invisible was tasked with acting as his spy to survey the Ten Commandments actions, as was the only such spy to return. Later informed him and his group about the devastation in northern Britannia, Camelot's downfall, and the goings on at the Great Fight Festival at Vaizel.

Deathpierce
She has been friends with Deathpierce since he was a child and he is the only one she allows to see her or will talk to.