At Yami High, a seemingly mundane day takes a dark turn when a cell phone rings and blood is spilled, initiating a deadly challenge. The stakes are high as Contractor Mikiya must curse-kill thirty individuals within thirty days to avoid a dire fate. Meanwhile, Curse-Breaker Saeyama races against time to uncover the killer's identity without becoming a victim of Mikiya's lethal curses. The ultimate showdown between these two forces of darkness unfolds, with only time holding the answer to who will triumph in the end.