"Decoding the Enigma of "Natural Man" in Mark Twain's Works" is an unexpected journey to the very heart of the utterly brightest American author, Mark Twain, the way he presented the phenomenon of "natural man" one of Jean-Jacques Rousseau's philosophy cornerstones. In this book, completely new for the genre, Taro Maeyashiki reveals the unique plan of Mark Twain's fantastic worlds of literary characters using the one of the most noble and philosophical topics prisms. Maeyashiki, noticing, as the thick conceptual fog dissipates around the concept of "natural man," explores how "natural man" can in fact be truly natural or free or innocent but at the same time, individual who has his sense of justice and injustice before a faceless society. Maeyashiki's work is impressive not only due to derivative because, by analyzing, he tried to mean Twain's perception of "natural man." This work is not only to do with the literary world but venture into Twain's internal essence analysis, his life, his philosophy, skepticism about the course of society development, and barely noticeable ideal simplification tendency, from the moral point of view. Referring to Rousseau's theoretical notion of "natural man," Maeyashiki writes that, essentially, Mark Twain was depicting the concept in his stories' characters. This book is the readers' dedication, as it allows us to look at Twain differently, through the high philosophical issues prism related to the essence of human nature and the destructibility of outer constrictions.