Ito Gingetsu (伊藤銀月) was a prolific Japanese author and journalist whose works covered military history, traditional martial arts, folklore, and Japanese culture. During the early twentieth century he became one of Japan's foremost popular writers on ninjutsu, presenting historical sources and oral traditions to a wide audience through books and magazine articles. His best-known work, Ninjutsu no Gokui (忍術の極意), remains one of the foundational modern publications on historical ninjutsu and influenced many later researchers, including Fujita Seiko and Okuse Heishichirō. Gingetsu also adapted his research for younger readers through publications such as Shōnen Club (少年倶楽部), introducing traditional ninja history and techniques in an educational and entertaining format. Although written for the general public rather than as academic studies, Ito Gingetsu's publications played a significant role in preserving historical knowledge of ninjutsu during the early twentieth century. His writings continue to be cited and collected by historians and researchers of Japanese martial traditions.