Summary of Ninja no Seikatsu

Published in 1963, Ninja no Seikatsu (The Life of Ninja) is considered the first serious academic study of the ninja from a sociological and historical perspective. Unlike earlier works that focused on the mythology or “magic” of ninjutsu, Yamaguchi Masayuki approached the subject as a formal historian.

The book’s primary focus is to deconstruct the social reality of the ninja. It explores:

• Daily Life: How ninja families lived, their status in the feudal hierarchy, and their domestic lives when not on missions.
• Economic Reality: Details on how ninja were employed, their wages, and their roles as both mercenaries and “mountain guerrillas”.
• Regional Differences: A comparative study of the Iga and Koka clans, examining how their unique geographies shaped their distinct styles of intelligence gathering and warfare.

Unknown & Interesting Facts

About the Author: Yamaguchi Masayuki

• Dual Expertise: Before he became a ninja scholar, Yamaguchi was an expert in Korean history. He lived and taught in Korea (then under Japanese rule) for years, serving as a teacher and editor before returning to Japan in 1945.
• The “Royal” Connection: During his time in Korea, he served as an editor at the Yi Wang Office (The Household of the Yi Dynasty), giving him a deep background in handling sensitive state archives—a skill he later applied to decoding secretive ninja records.
• Educational Superintendent: After the war, he wasn’t just a writer; he was a key figure in Japanese education, serving as the Superintendent of the Otsu City Board of Education in Shiga Prefecture, which borders the Koka ninja region.

About the Book

• The “Yamaguchi Stamp”: The red stamp you see on the colophon is a Ken-in (inspection stamp). Yamaguchi was known for personally stamping his first editions to verify their authenticity and ensure royalties, making copies with this stamp significantly more valuable to collectors.
• A “Forbidden” Bibliography: The first edition is prized for including a detailed ninjutsu bibliography that listed rare, sometimes “secret” family documents. In later 1980s reprints, some of this specialized data was condensed or omitted to make the book more accessible to a general audience.
• Academic Pioneer: Before this book, “Ninja Studies” (Ninshogaku) was not a recognized academic field in Japan. Yamaguchi’s rigorous research is credited with moving the subject from the world of children’s stories into university-level history.