Ten years ago, rifts opened in the city of Amatori, unleashing demons upon the world. To contain the threat, the "Great Wall" was erected around the city, turning it into a deadly prison. But sooner or later, the barrier will fall.

The government established an organization known as ARC, dedicated to training the "Boundary Breakers" — humans who have transcended the limits of ordinary existence. Among them is sixteen-year-old Yamimoro, trapped beneath the dome of hell together with his squad, Segunda.

Haunted by doubt and fear, he battles not only demons but also himself. Deep within his subconscious, an ancient demon named Iroshiki awakens, seeking to claim the boy’s body and soul. Now Yamimoro must search for answers: is he a hero, a victim… or merely a vessel for evil?

The world teeters on the brink of annihilation, and the choice of one teenager may determine the fate of all humanity.