The book on the left is entitled Ninpiden Volume 1.
This first volume is an exact replica of the Ninpiden printed on traditional Japanese rice paper.
The book on the right is entitled Ninpiden Kaisetsu, Kazo Bunken Shomoku Volume 2 (Explanation and Private Documents Table of the Ninpiden).
The second volume, modern printing, contains an explanation of the Ninpiden with a brief history of the individuals and family related to the author.
Also, an extensive listing of key historical Ninjutsu documents, with a short summary of each, up to the Taisho Era (1911-1925).
Included is 12 pages of close up photos of many of the scrolls and manuscripts mentioned.
The author of Volume 1 is Hattori Hanzo (1542-1596).
The author and editor of Volume 2 is Okimori Naosaburo, owner of the original Densho.
The publisher was Ueno shi Meitengai.
The printing date of both volumes is January 10, 1971.
This was a very limited edition printing and very rare with Okimori Naosaburo stamped seal on the last page.