Bad Girls Witches have long since had contact with humans so as to continue their lineage, but since medieval times, they have been driven underground in fear of another great witch purge. In the end, a contract was drawn up between Witches and X-Men, human men with high genetic compatibility with witches, so as to ensure the continued safety of both parties. In modern-day Korea, a pair of hapless half-witches are put under the guidance of fellow witch Hyo-Ran Lee in order to find the next X-Man.