I had assumed the title was a pun on "XXX" as in the kind of raunchy material in these books (Which are VERY ecchi by the by, and sometimes skirt the line of 18+ pretty closely with some panels and angles of Lucoa's clothing!) but it's a XX chromosome joke on her being a dragon "Woman."

Your mileage will probably vary based on how that joke makes you feel, because it's very ecchi and definitely not concerned with being politically correct. If you're here for dragon oppai, you're in the right place lol.