The local samurai of group Koka created organizations for self-government called “So”.
When foreign enemies attacked, they were able to fight with great solidarity of their organizations.
These situations led the local samurai to gradually develop, what we know today, Ninja Arts.
Even if they created their self-governing organizations, the area was subordinate to the ruling Rokkaku clan.
Therefore, such local samurai needed to find a way to coexist.
One of the characteristics of the Koka Ninja is they had a skill of using medicines and poisons.
A man, Mochizuki Izumo-no-Kami, was said to be the leader of Koka Ninja.
The mochizuki family was one of the most prominent clans with 53 Koka Ninja clan.
Mochizuki Izumo-no-Kami was involved in the campaign of Ashikaga Yoshihisa against Rokkaku Takayori, that culminated in the Battle of Magari.
Mochizuki is said to use Ninja Arts with smokes to upset the Ashikaga forces.