Photo/Illutration The recently discovered hand-copied versions of “Yonin,” part of the ninja strategy books “Bansenshukai” (Kazuki Endo)

NAGANO--Hand-copied versions of part of “Bansenshukai,” one of the three major ninjutsu (ninja art) strategy books, were recently discovered at the Sanada Treasures Museum here, leading researchers to ponder how they made it this far afield. 

“Bansenshukai” is said to contain comprehensive information on ninjutsu of ninja clans who were based in Iga in Mie Prefecture and Koka in Shiga Prefecture.

Yuji Yamada, an expert of ninja study who made the discovery, said, “The discovery in Nagano is very surprising because (such copies) had been thought to be in the hands of a limited number of families in Iga or Koka.”

He intends to research further why they were found in Nagano, which is far from both Iga and Koka.

The Sanada Treasures Museum has documents and other items related to the Sanada Family, who ruled the Matsushiro Domain, a feudal domain located in what is now Nagano Prefecture, from the 17th to 19th century.

Yamada, 55, a professor at the faculty of humanities at Mie University, found hand-copied versions of the first and second volumes of a book called “Yonin” at the museum.

Yonin is part of “Bansenshukai,” which consists of 22 books.

“Bansenshukai” were written during the Edo Period (1603-1867) and are considered an encyclopedia of ninjutsu.

The two hand-copied books that were recently found explain ways of surveillance or tricking people, such as how to collect information without resorting to hiding.

According to Yamada, as far as “Bansenshukai” books’ hand-copied versions that were made until the Edo Period are concerned, only around 10 have been discovered in three areas, which are Iga, Koka and Tokyo.

Both Iga and Koka are known as the “birthplace of ninja.”

In what is now Tokyo, hand-copied versions of “Bansenshukai” books were submitted to the Edo Shogunate.

The original “Bansenshukai” books haven’t been found.

The Koka city government has designated hand-written versions of “Bansenshukai” books as a city cultural property.

The Sanada Treasures Museum has more than 50,000 items related to the Sanada Family and around 17,000 of them are documents.

An official of the museum said, “We didn’t know what they were, but we kept (the hand-copied versions of ‘Yonin’) as part of documents related to Yukitsura Sanada (1791-1852), who was the eighth lord of the Matsushiro Domain.”

On why ninjutsu books on Iga and Koka ninjas were found at the museum, Yamada said that handwriting characteristics in the hand-copied versions lead him to believe that they were copied in the late Edo Period.

From this assumption, Yamada links the hand-copied books to Yukitsura.

“Yukitsura was passionate about military strategies, and it’s said that he knew experts in the area in Edo,” Yamada said. “He might have collected various things related to military skills, including by hand-copying ninjutsu books in Edo.”

He added, “I would like to continue researching by comparing (the hand-copied books he found) with other hand-copied books of ‘Bansenshukai,’ for example.”

Sayuri Yamanaka, a researcher at the museum, said that Yukitsura was the son of Sadanobu Matsudaira, who was the “roju” (elder of the Edo Shogunate).

“He (Yukitsura) had a connection with people in the Edo Shogunate, too,” Yamanaka said. “He might have learned (ninjutsu) as military strategies, when collecting information for the military reform at the time. I’d like to wait for the results of further study (on the recently discovered books).”

(This article was written by Kazuki Endo and Naoyuki Mori.)

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