The Final Devil of the Supernatural hunter highschool

Fifteen years ago, a demon plucked the forbidden fruit and ate it. He is in love with his host, and is willing to abandon his dimension for her. To add insult to injury, he is the one and only, demon king: Orzar His action came at a cause, tearing space and time, creating a gigantic wormhole, connecting our world, to another, to hell. Opening a slaughter field as demons, monsters, spiritual beings. Beings of myth and legend flooded our world. Starting a war between dimensions, millions were dead, and the numbers are still rising. Those occupations that seems like joke and witticism started to become the list line of defense from those beings. Exorcists, priests, taoist hunters stood out, protecting humanity and finally forcing them back to their dimension, temporary. Those who are still left were taught to learn knowledge of such, humanity needed to arm to the teeth to fend off the second invasion, that is happening fast. With Fei being one of them, a what seems like a weakling, but someone with a very complicated and in fact dangerous background...