The book recommended to me when I was doing Ninjutsu was "Ninjutsu: History and Tradition" [1]. It's written by Masaaki Hatsumi himself. [1] http://www.amazon.

The book recommended to me when I was doing Ninjutsu was "Ninjutsu: History and Tradition" [1]. It's written by Masaaki Hatsumi himself. [1] http://www.amazon.co.uk/Ninjutsu-History-Tradition-Masaaki-Hatsumi/dp/0865680272/ref=sr_1_7?ie=UTF8&qid=1357648523&sr=8-7 http://www.amazon.co.uk/Ninjutsu-History-Tradition-Masaaki-H...