The Succubus is a demon who has adopted a female form in order to seduce men so as to absorb their life energy. She currently resides in the first chapter (Lust) of the Book of Eibon, after an unsuccessful confrontation with Noah resulted in both her permanent imprisonment and addition to his collection.
In a further attempt to attract men in addition to her rampantly seductive appearance, the Succubus conducts her movements in the most perverted way to expertly accentuate the most bewitching and attractive aspects of her female form.
Befitting her need to entice men in order to fulfill her respective desires and vice, this particular demon has assumed an alluring form that she believes best caters to a typical man's wants: A young and voluptuous female with an ample bust. Her softened facial features are contrasted by the stark addition of a vertical line descending from either of her eyes (Which are shown with heart shaped pupils); these lines are connected by a horizontal line that runs over the bridge of her nose, together creating an "H"-shaped marking.
The rest of her face is concealed beneath a layered and spiky hood, featuring two prominent horns protruding from the sides. Further placing emphasis on her seductive qualities, the Succubus wears the bare minimum of clothing; consisting simply of skintight gloves and stockings decorated with "H"-shaped accents at their openings and a revealing apron that exposes the majority of her back, except for where a few small strands keep it attached to her body. This wardrobe choice's open back also prominenty displays a "certain aspect" of her appearance. A small, slightly coiled devil-like tail extends from just below the small of her back.
The numerous "H"s on the Succubus' person are most likely a reference to the Japanese word ecchi, denoting sexually explicit material or behavior; "ecchi" is a spelling-out of the Japanese pronunciation of the letter H, and could have originated as a polite codeword for hentai in the 1960's.