忍術と修養 Ninjutsu and Cultivation (Page 136-139) from the book 忍びと忍術 Shinobi to Ninjutsu by 山口正之 Masayuki Yamaguchi 忍術と修養 Ninjutsu to Shūyō (Ninjutsu and Cultivation) Of the three ranks in the… Read More »History of Ninjutsu: Ninjutsu and Cultivation