In Shakugan no Shana, there exists a dimension called the Crimson World. Its residents come to the human world to devour people's Existence. When someone's Existence is devoured, not only will he/she disappear, he/she is effectively erased from history. When they come, they usually use a magic seal which time-stops everything in a large area, before drawing the Existence out of people. The most powerful Crimson Lord is Alastor, Flame of the Heavens. Just by manifesting his physical form, he consumes an enormous amount of Existence, maybe cities of people.