The Watanabe Documents(150 pages) was discovered in 2000. Koka city has researched the documents since last year and they released some info.
According to Sankei's report, the documents contain exprosive's recipe, instructions for Musket and horseback riding, and some occult arts.
During Edo period, they were hired as "Oshinobi-yaku" by Owari Tokugawa clan.
"Oshinobi-yaku" was like part time job, they were called only needed.
Otherwise, they were living as common farmer.
Nikkei's report says, Oshinobi-yaku was secret contract.
They found 10 written pledges of keeping it secret from family and friends between 1700 ~ 1829.
It seems Ninjutsu documents were only 17 pages(include the pledges?)
Koka city is going to publish the documents.