Delilah, a ten-year-old girl, was kidnapped by demons to be used as a vessel to revive the Demon Lord. Forced to perform a summoning ritual, she lost consciousness during the horrific and terrifying process. Little did they know, she had already been possessed by the high-ranking soul, causing the ritual to fail. When she awakened, she found a strange creature in a suit in front of her—the Demon Lord, Tai Walpurgis, from a thousand years ago. Visible to no one else, Tai and Delilah now faced their struggles together. Thus began the rise of Delilah, guided by Tai Walpurgis, as she grew in power and influence to become the Demoness.