VGFacts

Kunoichi is inspired by the Sanada Ten Brave, a legendary group of ten ninja created by Yukimura Sanada to serve under him. Kunoichi was likely created as a representative for the legendary group overall. However, members of the group do appear in the game as body guards.

Sources:
http://koei.wikia.com/wiki/Kunoichi
http://koei.wikia.com/wiki/Bodyguards_(S...i_Warriors