Black Gate Omnibus

In this world, there exist paths which souls must pass through called Gates. Typically, when a person dies, the soul escapes the body, passes through the White Gate, and moves on into the next world. At times, however, the Black Gate opens. The Black Gate does not wait for one to die and forcefully draws out the souls of living bodies. Causing unexplainable accidents and fires, the Black Gate continues to devour innumerable souls. However, there also exist the Mitedamashi, the chosen ones able to see the Black Gate and prevent the destruction it causes. This is their story.

Source: Anime News Network Encyclopedia