The author of the novel Zero's Demon Envoy is Shimada Sho. This novel was a fantasy adventure novel that told the story of the protagonist, Charles, experiencing various adventures and challenges in the foreign world. The novel had been published since 2007 and had seven separate volumes. There was also an animation and a manga. Although the plot of the novel was rather complicated, the author, Shima-Gado, had been updating it continuously and had not announced the end of the story yet.