It could be a new character created specifically for the fanfiction. This character might be an outcast from a powerful clan in the Hunter x Hunter world, with a grudge against the hunters, thus being named the 'white devil' due to their menacing and unpredictable nature.
The 'Devil in the White City' is a very interesting piece of fiction. It combines the historical context of the World's Columbian Exposition in Chicago with a dark and sinister plot. The story shows the contrast between the grandeur of the fair and the evil deeds of the 'devil' figure in the story.
Sure. The book is imaginative fiction. It takes historical settings and adds fictional elements to create a compelling and entertaining tale for readers.
The book is nonfiction. It provides a detailed account of actual occurrences and people during that time period. The author did extensive research to present a factual narrative.