Since ancient times, humans and demons have coexisted. But the rules of the world have changed, leaving humanity with little path to cultivation and making the demonic path just as difficult to climb.
As the old saying goes, "When things grow old, they become spirits. Those who can take human form and beguile others are demons." Thus, all demons steal the powers of heaven and earth to live on in this world.
Yet some among them refused to live out their days quietly, dreaming instead of breaking the world's rules. They turned their cultivation into a rule of the world, storing it within their demon cores. Each generation passed the cores down, adding another rule to them. These outliers came to be known collectively as "Fallen Demons."
By chance, the male lead, Su Ling, fuses with the last Fallen Fox Demon core, transforms into a girl, and begins a brand-new life.
