Quote Originally Posted by Munsu
If I remember correctly, in the first episode when Kaaya was here she was visited by that blue spirit from the first season that always showed up to Neeba. I wonder who that is... it hasn't been revealed right?
Not completely but we do have some info on her:

She's the witch succubus, Druaga's former lover who was found by neeba in hibernation somewhere underground and supplied him with the info about the mystical tower.