The Koka ikki emerged from the wreckage of the Onin War. After centralized authority collapsed in Japan during the late fifteenth century, banditry, peasant uprisings, and predatory raids by local warlords made life dangerous across the country. Property rights meant nothing without the force to defend them. In the hill country of southern Omi Province, defeated jizamurai -- minor samurai who had lost their positions -- took refuge among the local population and began training them in martial arts. Together, these warriors and farmers built something remarkable: a district-wide league of autonomous clans that pooled their strength without surrendering their independence. The ruling families formed what was called the domyochu, and their governing body was the Koka-gun Chuso, the General Assembly of Koka District. Elders from the fifty-three clans met in succession at three shrines on the outskirts of what is now Koka City, debating strategy and settling disputes without a central ruler.

The chaos of the Sengoku period created a booming market for mercenaries, and the Koka clans were well positioned to fill it. Their mountain terrain had forced them to develop unconventional warfare techniques -- stealth, infiltration, intelligence gathering, sabotage -- that became synonymous with the word ninja. The most famous clan member, Wada Koremasa, controlled his small valley with the authority of a daimyo despite holding no such title. The individual family units, called so, combined into the Kashigawi sanbo-so, a three-member league, and these leagues linked together into the district-wide confederacy. This structure gave them flexibility: clans could hire out their warriors independently while maintaining collective defense. After the Tokugawa shogunate consolidated power, the Koka ninja transitioned from battlefield operatives to spies and bodyguards. Their last recorded combat deployment was at the Shimabara Rebellion in 1637. The very last documented use of Koka ninja in service to the shogunate came in 1853, when they were allegedly dispatched to investigate the arrival of Commodore Perry's Black Ships.

The spiritual life of the Koka district ran as deep as its political independence. The dominant religion was Shugendo, a syncretic practice blending Buddhism and Shinto, particularly the Tendai and Shingon schools. In the forested hills, militant mountain monks -- yamabushi -- dedicated themselves to asceticism and esoteric ritual, their physical endurance training overlapping with the martial conditioning of the ninja clans. A 1475 document of donations to Aburahi Daimyojin, the patron deity of Koka, names members of the samurai-shu among the contributors. Records from 1571 show the Koka-gun mediating a dispute between the Handoji -- the main Shugendo temple in the district -- and the Shingu and Yagawa Shrines. Takigawa Castle, held by the Ohara clan, sat directly across from the Tendai temple Rakuyaji. Religion and warfare, temple and fortress, existed side by side in these hills. The monks prayed, the warriors trained, and both answered to the assembly.

The Koka ninja's most celebrated service came in 1582, during the crisis that followed Oda Nobunaga's assassination at Honnoji. Tokugawa Ieyasu, the future shogun, found himself stranded in hostile territory with a small retinue and needed to reach his home province of Mikawa alive. Bands of ochimusha-gari -- masterless warriors turned bandits who hunted fleeing soldiers -- prowled the roads. The Koka ninja joined Ieyasu's escort group, neutralizing threats and guiding the party through dangerous terrain until they reached Iga Province. There, the Iga ninja -- the Koka clans' famous neighbors and sometime rivals -- took over the escort, accompanying Ieyasu safely home. This act of loyalty cemented the Koka clans' relationship with the Tokugawa. But their independence was already ending. The confederacy's independence had already been broken by Nobunaga in 1574; after his death, Toyotomi Hideyoshi placed the district under his vassal Nakamura Kazuuji. The warriors who had governed themselves for over a century became ronin -- masterless samurai adrift in a newly unified Japan.