The Bansenshukai (Sea of Myriad Rivers Merging) is a multi-volume secret written transmission (densho) of Iga and Koga Ninjutsu. It was compiled by Fujibayashi Yasutake (also, Yasuyoshi) of Iga in the fourth year of En'o (1676). The Bansenshukai collection includes one volume of introduction, question and answer section, and a table of contents; two volumes on thought and philosophy; four volumes on leadership; three volumes on Yo; five volumes on In; two volumes on astrology; and five volumes on weapons. The Koga version has twenty two chapters bound in ten volumes with an additional one volume. The Iga version has twenty two chapters bound in twelve volumes with additional four chapters in four volumes attached to it.
The Bansenshukai is a written transmission of philosophy, military strategy and tactics, astrology and weapons that are identified specifically with Ninjutsu. Although the author of the Bansenshukai was influenced by Chinese thought, and even indicates a connection to Chinese military traditions, he presents the material as the ultimate accumulation and perfection of Ninjutsu knowledge--as the name Bansenshukai itself suggests.
A limited number of hand written copies of the Bansenshukai were offered to the public after WW2, but the publisher stopped producing more copies and there are none available for purchase. For those interested in reading the Bansenshukai in its original language (which is not modern Japanese, rather a form of Japanized Chinese called kanbun), some major national and university libraries hold a copy of the collection. Selected translations of the Bansenshukai published in this site were made from a hand made copy (shahon) of the original text. A full translation is not planned for this site but would be available sometimes in the future in a printed form.