This book is not a martial arts manual. It is not about how to became a ninja and is not a 10 days black belt course. Although ninjutsu has been already introduced in the Western world since the 80s, there are still a lot of misconceptions and discussions about it. Many have taken the advantage of the 'shadow' of information to create and claim their styles out of a black costume and some street fighting techniques. Others are still fascinated by the word 'ninja' thinking about magical power and invincibility, while someone else would even think about killers or thieves. If we ask ten people in the street what a ninja is, most likely we will get ten different answers. This book comes after over 20 years of research into martial arts and Asian culture. It offers a unique insight into the classic art of ninjutsu; from the places where it has originated, explained through the words of a mentor and researcher who has dedicated his whole life to it. It includes pictures of places of historical significance and milestones of the evolution of this art. It also includes translated excerpt from the "BanSenShuKai" the ninja secret manual, compiled in the 17th century during the Edo period. It is a journey into the "Intelligence Services" of the feudal Japan discovering the way, the methods and the skills of people who played a great role throughout the history, at the shade of Generals and Warlords. The book is presented to give a better understanding about ninjutsu as an art and as a way of living. It is not addressed to martial artists only but to anyone who would like to find more about the intriguing "Shadow Warriors" from an historical, cultural and practical perspective. From the teachings of great generals, astrologers and priests, ninjutsu has developed a unique way to make full use of the human wisdom and potential that could be of great value even in our modern society.