The story takes place in a world overrun by ghosts, where night devours everything. Day and night are no longer distinct, and the sky screen remains dim all year round. Whenever night falls, all sorts of uncanny ghosts emerge from the darkness, threatening humanity's survival. To fend off these ghosts, powerful Night Watchers are summoned into being. They possess special abilities that let them stand against the ghosts, but becoming a Night Watcher also means living with the darkness for the rest of one's life and bearing a curse that can never be lifted.
