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. 3 - "Warrior Path of Togakure" deals with the warrior's quest for enlightenment, invisibility through changing identity, ken-tai-ichi-jo body and weapon as one, special section on kuji-kiri intention channeling.