Yukiteru Amano, a solitary middle schooler, is thrust into a deadly survival competition orchestrated by the god Deus Ex Machina, where the ultimate prize is divine power. Tasked with outlasting 11 other participants, each armed with a Future Diary foretelling the future, Amano wields a unique Random Diary that provides precise details of his surroundings. Reluctant at first, his alliance with the peculiar and infatuated Yuno Gasai, a classmate and fellow diary owner, becomes crucial for his survival. As the brutal contest unfolds, dark truths emerge, reshaping the very essence of this macabre game.