A noble knight Altear Chernobog under the emperor's orders went to war to kill her companion and beloved Ain Estarot, the 'Son of the Demon', and in the end she was killed by him. Just as she was about to break through the memory fragments and go to the underworld, she opened her eyes and saw her father, who had died years ago, standing before her?! Altear, who returned to his childhood as if it were a lie, and thinks. The only chance to save Ain, who has been oppressed by humans all her life.