Everyone has a gem in their heart, showing their hopes, dreams, and wishes. But, when a gem is corrupted, that holder becomes a monster of the devil. But these monsters hide in the shadows, catching, killing, and eating their victim's gem. The devil has 7 main monsters, generals per say, of the 7 worst sins. But, a secret school was formed to fight these monsters and battle the devil, and so this is where our story begins, with Charity being sucked into this war.