Season 1

Hibiki Kuze, is waiting for his friend, Daichi Shijima, after finishing their practice exams. While discussing their future, Daichi introduces and registers them onto a recently popular website called "Nicaea", a video delivery site that allows people to see videos of their friend's death. Later, at the train station, they receive videos from Nicaea that show both of their deaths by an oncoming train at that exact station. Shortly after, before the train arrives, an earthquake occurs, causing the incoming train to derail and cause the same devastation they saw in the videos. On the verge of death, Nicaea offers Hibiki a second chance to live and a Demon Summoning App is forcefully downloaded into his phone. He and Daichi awake to find the station in ruins with most of the people dead. They then witness vile wolf-like creatures eating the corpses of the recently deceased.