The Demon King Ahriman faces a unique dilemma: his daughter, Dou, possesses an unusual trait - a deep affection for all beings, even their sworn enemies, the humans. This unexpected love and compassion force Ahriman to pause his world-conquering plans, concerned that Dou's kindness is unfitting for a demon's offspring. Rather than scold her, Ahriman surprisingly praises Dou for her altruistic acts. With the assistance of his capable aide Jahy, who becomes Dou's mentor, they embark on a mission to eradicate her compassionate nature. Their goal: transform the sweet, lovable girl into a cold, ruthless little demon, shedding her endearing qualities for a darker essence.