In the Shoninki written by Natori Masatake in 1681, he documents the 5 types of spies called the Gokan. These five types of spies are from China, and can also be found in the Art of War written by Sun Tzu. In the Budo Ryu Kai we use the term "Shinobi Gokan" when discussing the 5 types of spies written in the Shoninki.

 

Inko no kan (因口の間) Local Spy

Nairyo no kan (内良の間) Inward Spy

Hantoku no kan (反徳の間) Converted Spy

Hicho no kan (死長の間) Doomed Spy

Tensei no kan (天生の間) Surviving Spy

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"The above are the so-called Gokan, five types of spy and these are called shinobi in Japan. Their philosophy is universal to both countries, even though they have been labeled differently in China. This is the end of the five types of spy and their origin in China."

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- Natori Masatake (1681) Shininki

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