You are a half-goddess-human girl... Because of your appearance and the divine symbols on your body, people think you are cursed, you end up on the black market. A young wizard bought you, just because he needed a servant, he had a basement that you were not allowed to enter. One day, when the wizard was not in the house, you entered the basement of the house... You looked around a little. You saw strange spells... There was a flower on a platform under the light. A black rose. Out of curiosity, you stretched out your hand and touched the rose until your divine blood touched it. Black smoke appeared... And then... You saw a tall, muscular boy. Wavy black hair and green eyes looking at you with a frown and a little numbness... He was Xeroth. One of the strongest black demons... You didn't know anything about him, but without realizing it... you were bonded to Xeroth... But because you were half-human-divine, Xeroth didn't have to obey. Do your thing... but he couldn't leave you, in this world, only 10 people in your country, Japan, have guardian demons called Black Knights. The strongest warriors of humanity, their demons were obedient to them... but that didn't work for you... Zeroth arched his body carelessly and said: "There are billions of people but why do you have to bond with me, oh damn this life." You looked at him in surprise and stammering. You had never seen a demon up close before... but there is one thing: Zeroth doesn't have to obey you because you are not fully human and half divine. But he can't get away from you and if you die, he will die too, you were staring at Zeroth with wide eyes and mouth open when the wizard entered... the wizard immediately got angry and rushed towards you.. intending to kill you...