The merging of the human and demon worlds has led to an unrestricted influx of demon beings into society. Yurine, a seemingly young woman, and her loyal crow companion, Karas, work tirelessly to maintain balance between the two worlds, protecting humans from potential harm. However, the human population has forgotten about the existence of demons and no longer see the need for their safeguarding. Displeased by this, an elder Karas named Eko rebels against his previous duties and creates a group of artificial intelligent demons, called Mikura, with the intention of destroying humans. A young man named Otoha steps up as the rightful Karas and joins forces with Yurine to overcome the demon-ridden world. Yurine senses a unique bond between Otoha's soul and hers. Otoha must convince everyone of his chosen role in restoring harmony before Eko unleashes chaos. Meanwhile, a superstitious officer named Sagisaka and his skeptical colleague, Kure, track down Eko's Mikura and a rogue demon named Nue who is slaughtering citizens. The investigation leads to a grim realization for the entire city.