She was picked up by the hall master when she was a child, and was trained by the hall master to become a peerless killer. She was named Butterfly because there was a butterfly on her chest. He was a dazzling star since he was a child, just because he was the prince of the fairy world, and was named Silver Wolf because he had a silver wolf on his shoulder. This time, her mission was to kill him, but she was no match for him and developed feelings for him. At this time, he also told her that he loved her. What should she do? He is a fairy, but she is just a devil...