Magic exists in this anime but it isn’t the traditional kind you would expect to see in a realm of fantasy. On the contrary in this anime, magic is being used as a resource. It is used in various industries including the sciences, medicine and the military. However, there is a drawback, prolonged exposure to magic transforms the magic user into a powerful demon, impervious to traditional weapons. The demons are ravenous beasts bent on killing everything in sight. Their society has come to accept the risks to reap its benefits. They have even developed a kind of task force to neutralize these demons. They are referred to as tactical sorcerists; which is actually a licensed profession in the anime. These tactical sorcerists are like a SWAT team; they also wear protective suits referred to as “Strait Jackets”.
The strait jackets are metal armored suits that protect the tactical sorcerists from the damaging effects of the magic they have to use to subdue the demon threat. Although it isn’t foolproof, there is a chance that even the tactical sorcerists can become demons inside the strait jackets. But we soon meet someone out of the ordinary; namely Leiot Steinberg. Leiot as of now is essentially an unlicensed rogue for hire.
I challange the laws of nature & reason, by summoning the power that is forbidden. – Leiot Steinberg
He is accompanied by a half-demon and half-human girl; who becomes an assistant to Leiot after her parents were killed. She applies the magical protections upon him and assembles the strait jacket. Unfortunately, the demon threat is getting worse with time and magic use and now even the tactical sorcerists themselves need rogues like Leiot to stop the rampaging demons.