Big surprise there. Kentaro Yabuki made both To-love-ru and Black Cat so Eve and Yami-chan are essentially the same person in every respect but name.
Same basic looks, same withdrawn personality, same powers, same mode of dress, they even both have crosses on their dresses, though GD's is a cutout and Eve's is some kind of brooch or ornament. There's even a scene in the manga where the girls take GD clothes shopping and one of the outfits she tries on is Eve's black dress.
