Koga-ryu school (甲賀流)
Koga-ryu (or Koka-ryu) is the most famous school of ninjutsu (ninja technique) along with Iga-ryu, but it is the name that refers to collectively the schools originating from the Koka region in Omi Province and the school named "Koga-ryu" did not exist. Koga, originally pronounced "Koka," is a toponym, but only when referring to the ninjutsu, the mistakenly pronounced "Koga" has become common.
Iga-ryu exists in the region separated by only a mountain from that of Koga-ryu.
It originated from today's Koka and Konan Cities in Shiga Prefecture. The people of Koga-ryu were usually engaged in farming or peddling to collect information in various places and, once called, they went to the war fronts or the rear of the battlefields to engage in espionage. Koga-ryu was highly skilled at dealing with medicine among the ninjutsu schools, a vestige of which can be seen in the fact that many pharmaceutical companies are located in Koka even today.
Though Koga belonged to the Rokkaku clan, it formed a soson (a community consisting of peasants' self-governing association), in which all issues were decided and managed by majority (council system). This was quite unusual at the time even at the nationwide level.
In the late Muromachi period, the Sasaki Rokkaku clan of Omi Province steadily built up the military force with the Kannonji-jo Castle as their headquarter and started to take light of the orders from the Ashikaga shogunate or even ignore them, therefore Shogun Yoshihisa ASHIKAGA sent an army to subjugate the Rokkaku clan in 1487 and a battle broke out. This battle is called 'Magari no jin'.
When Yoshihisa mobilized daimyo (Japanese feudal lords) from various provinces and got close to the Kannonji-jo Castle, the headquarter of the Rokkaku clan, the father and the son Hisayori and Takayori Rokkaku moved to the Koka-jo Castle to avoid a direct confrontation. Then, Yoshihisa moved the headquarter to Magari no Anyo-ji Temple located in Kurita-gun County and attacked the Koka-jo Castle, and the Koka-jo Castle fell, but the father and the son Rokkaku escaped and ordered the Koga warriors who followed them to resist adamantly against Ashikaga by guerrilla warfare in the mountains. It is said that Koga warriors took a geographical advantage in the mountains to make various surprise attacks against the bakufu army and tormented them by using fire and smoke on Yoshihisa's headquarters during the night.
So, the battle did not easily end, but the death of Yoshihisa in battle in 1489 marked the end of the three-year conflict, and the Rokkaku clan survived. The name of Koga warriors became well-known throughout the country because their elusive and effective guerrilla warfare and high combat ability in this battle were so impressive. The 53 families of jizamurai (literally, soldiers of the land) that participated in this battle were called the "53 families of Koga" (among them, the families which received a letter of commendation from the Rokkaku clan for taking part in the battle and were valued were called the "21 families of Koga") and they were active in both intelligence and fighting activities under the Rokkaku clan until the Koka region was seized by Nobunaga ODA.
After the Koka region fell under the control of Hideyoshi TOYOTOMI from Nobunaga ODA, the Koga warriors were mainly missioned to spy on Ieyasu TOKUGAWA. This fact was featured in storytellings or Yomihon (books for reading) in the Edo period, in the form of "Iga ninja force versus Koga ninja force" stories. Actually it was a war by proxy between Tokugawa and Toyotomi, but because of this the confrontation plot of "Iga vs. Koga" often appears in novels or ninja cartoons even today.
The former residence of the Koga Mochizuki clan (Omi Province), the leader of the 53 Families of Koga is extant as Koga-ryu Ninjutsu Yashiki at 2331 Ryuboshi, Konan-cho, Koka City (which is different from Koga-no-sato Ninjutsu-mura [Koga Ninja Village]). The residence built during the Genroku era (from 1688 to 1703) looked like an ordinary farmer's house, but the inside has traps such as rope ladders, pitfalls, revolving doors and underground passages. The weaponry and other historical artifact used are also displayed.