The "Ninja" series 1-5, featuring the beautiful full-color cover artwork of Gregory Manchess, published in the years between 1980 -1989, offers the higher-level philosophical aspects of the ninja arts with a look at the combat techniques in action. These were the original volumes that identified Stephen K. Hayes as an extraordinary writer-scholar willing to explore the spiritual significance of authentic warriorship to a depth unapproached by any martial arts writer before. Ninja Vol. 4 - "Legacy of the Night Warrior" deals with the hstory of the ninja, flow and advanced martial arts skill, the 5 elements of invisibility, self-defense techniques of kunoichi female ninja, drills for sensing the intentions of the attacker, interview with Stephen K.