Koka, which is situated in the south of Shiga prefecture, and Iga in Mie prefecture, were located close to each other. However, during the Sengoku period the situation was different. In the border between the two territories there was a check point. At that time, society was rough and the law was weak. It was a period of time when Samurai had the right to kill commoners for perceived affronts and there was nothing commoners could do about it but cry.

Located in Naniwa (Osaka) and in the capital (Kyoto), Nobunaga, Hideyoshi and Ieyasu often used the services of Koka ninja in order to gather information. Ninja travelled back and forth between regions and gathered information. In that period, an official language had not get been established. Language and accents were different even in regions situated close to each other. People could easily recognize strangers.
It was a ninja’s job to bring the information they collected back to their master as quickly as possible. During that time, it was difficult to travel incognito.