Books like Secrets of the Ninja
Ashida Kim
Secrets of the Ninja is 152 pages, about 2 hours 47 minutes at 250 words a minute.
7 books to read next
How long each takes
Chinese Gung Fu 2.1 h 
The Art of Shaolin Kung Fu 4.2 h 
Book of Ninja 9.7 h 
Combat Skills of the Lin Kuei 2.6 h 
Ninjutsu, the Art of Invisibility 2.3 h 
Tantojutsu 1.7 h 
The Ninja and Their Secret Fighting Art 2.9 h Bar height shows length. Estimated at 250 words a minute.