Five thousand years ago, the Demon King came, and with him came humans and superpowers with special abilities. The Demon King ruled for a long time, and all living beings lamented. Finally, a hundred years ago, the brave and his teammates defeated the Demon King at the cost of their lives. The Demon King disappeared since then. In the past hundred years, the Demon Race and the Human Race, which had lost their ruler, lived together. Naturally, not all demons without restraints are willing to coexist peacefully with humans. Therefore, demons, humans, supernatural beings, and half-demon races have established an organization to manage special races such as demons and supernatural beings - the Special Incident Management Bureau. However, this is in the face of official explanations, and the true purpose of establishing the organization must not be known. . . . .