Shakugan No Shana: The Movie

Shakugan No Shana started off with an interesting concept. There are forces unseen that feed on human energy, killing said humans. In order to stop the world from going out of balance Flame Hazes are dispatched to kill off the threats and put in place Flames, the remnants of humans now dead to fill in for the deceased. Flames have all the deceased’s memories and quirks but does not know it’s actually a flame.