Ninjas were required to be proficient in at least the "eight gates" of ninjutsu.

The ninja were required to master at least the "eight gates of ninjutsu," including kiai, bone techniques, sword, spear, shuriken, fire techniques, yugei, and kyumon.

They were undeterred by adversity and continued to devise ways to live out of their suffering.

In this book, Yoshiaki Hatsumi, who himself succeeded to the 34th head of the Togakushi school of ninjutsu after 15 years of training, passes on the "wisdom of life" of the ninja who survived in the world of ninja to those living today, accompanied by rare photographs.

Rare photos of Yoshiaki Hatsumi in his younger days are included.