Japan's hottest service is Nicaea, a website that sends your friends a picture of your death before it happens. Daichi and Hibiki are two teens who didn't expect Nicaea to actually be real – that is, until the boys receive an email about their demise, and die shortly after. On the brink of going to the beyond they're given a choice: expire, or have a second chance at life. And so the two awaken to discover the city's been destroyed and they now have the ability to summon demons – an ability that a secretive branch of the government insists they use to help combat an imminent threat. For unless summoners like the teens put a stop to otherworldly invaders destroying the planet, the world will soon disappear...