Kimihiko Kimizuka, a self-described trouble magnet, spent three years as assistant to Siesta, a self-proclaimed master detective who fought a secret war against an organization of pseudohumans called SPES. One year after Siesta's death, Kimihiko is trying to live as an ordinary high school student when his classmate Nagisa Natsunagi tracks him down and asks for help finding someone — a request that pulls him back into the world Siesta left behind.