When the demon king fell in love with a vampire and gave birth to a cambion 500 years ago, it led to the formation of a secret organization 300 years later and the cambion was sent to the mortal world to deal with the organization.The immortal realm and mortal world have always existed aloof from each other and therefore maintained a peaceful coexistence for over tens of thousands of years, but the immortal supreme of the immortal realm suddenly decided to make the legendary Phoenix appear in the human world just because there was no pure hearted immortal to take up that position.Nancy White happened to be that unlucky human that was chosen as the Phoenix because her mother was pure hearted and she was automatically the same. Her fate was already entwined with that of the cambion even before she was born, leaving her with an inescapable tragic fate.