Within a particular institution, lurks a gruesome past: a decade prior, an assortment of pupils fell victim to a series of savage and inexplicable slayings. The word on the grapevine is that it was the fallout from the "Book of Demise," a tome replete with fables and legends. Allegedly, the "Bookmark of Demise" injects reality into whatever page it occupies.
A pack of four rumor-mongering comrades—A-ya, a secluded boy who derives pleasure from generating such rumors; B-ko, a fashionable girl who feigns courtesy around others; C-ta, a sensible boy who happens to be A-ya's longtime friend; and D-ne, a taciturn and introverted girl—all members of said institution, manage to procure the Book of Demise by executing the required ritual. Unwittingly, they adjoin the Demise Game, and ultimately realize they have bitten off more than they can chew.
In order to survive the game, they must pinpoint and expose a turncoat among their ranks. Simultaneously, the Bookmark of Demise works on actualizing these myths, divulging a subtle link to the events of 10 years prior, and constructing a haunting quagmire of untruths and deceit.
