History of the Koka Ninja
Origin Legend
The origins of the Koka ninja are unknown, but one legend connects them to Prince Shotoku (574–672), an influential figure celebrated for his many contributions to Japanese culture. He reportedly had a servant from Koka named Otomono Sabito, who was highly skilled as a spy. However, the first mention of ninja in written texts does not appear until the fourteenth century.
Sengoku Period (1467–1568)
Local autonomy developed in the Koka area because the daimyo had little power over the area—an unusual situation at the time. The community formed groups based on blood and territorial ties and set up a self-governing organization known as the Koka Gunchuso. This self-regulation, along with the collective defense strategy of the region, was crucial in maintaining stability and preventing the rise of a single dominant power.
Warlords from other regions hired Koka ninja mercenaries and relied on their intelligence-gathering skills to fulfill their strategic ambitions.
First Significant Battle (1487)
In 1487, shogun Ashikaga Yoshihisa (1465–1489) launched an invasion of the Rokkaku domain of Omi Province (present-day Shiga Prefecture). The Koka ninja rallied around the Rokkaku family, and some ninja used surprise tactics to repel the shogunate’s army. Twenty-one of them launched a particularly daring night raid, injuring Yoshihisa. These attacks brought members of the Koka clan to wide attention, and the ninja families who had participated in the battle were revered.
Trusted Supporters of Tokugawa Ieyasu (1562)
In 1560, Tokugawa Ieyasu (1543–1616) gained his independence from the Imagawa family, to whom he was tied by marriage. After allying himself with the powerful warlord Oda Nobunaga (1534–1582), Ieyasu asked the Koka ninja for their support in attacking the well-fortified Kamigo Castle (Aichi Prefecture) in 1562. Around 200 of the Koka ninja helped to infiltrate the castle, killing Udono Nagateru (unknown–1562), the lord of the castle and part of the Imagawa family. Nagateru’s two sons were taken hostage, and Ieyasu exchanged them for the safe return of his wife and child, who were being held by the Imagawa clan. Ieyasu is believed to have written to the Koka ninja to thank them for their part in this successful outcome.
Assisting in Ieyasu’s Escape (1582)
On June 2, 1582, Nobunaga was unexpectedly attacked by his retainer Akechi Mitsuhide (1528–1582) and died at Honnoji Temple in Kyoto. Mitsuhide’s forces tried to prevent Ieyasu from returning to his base in Okazaki (Aichi Prefecture), and the ninja offered Ieyasu sanctuary when he passed through Koka, thereby strengthening their relationship with the Tokugawa family. Nobunaga’s death was avenged two weeks later when Mitsuhide was defeated, paving the way for Ieyasu to eventually become shogun in 1603 and unify Japan.
Toyotomi Hideyoshi Punishes the Ninja (1585)
Toyotomi Hideyoshi (1537–1598) was another of Nobunaga’s retainers who rose to a position of power. In 1585, he ordered the Koka ninja to build a levee as part of a flooding attack strategy. The levee collapsed, causing a flood. The ninja involved in building the levee were blamed and stripped of their land. Some remained in Koka to make their living as farmers, while others left the region in search of other work.
Siege of Fushimi Castle (1600)
The siege of Fushimi Castle was a small but historically significant battle leading up to the Battle of Sekigahara, which ended the turbulent Sengoku period. Torii Mototada, one of Tokugawa Ieyasu’s retainers, entered the castle to defend it. For 10 days, he and his household were under siege by military commander Ishida Mitsunari (1563–1600) and his forces. A group of ninja known as the Koka 100 participated in the battle at Fushimi Castle on Ieyasu’s side. Their efforts allowed Ieyasu to concentrate on more strategic battles. After Ieyasu became shogun of Japan in 1603, he invited the surviving members of the original Koka 100 to serve in the defense of Edo (modern-day Tokyo).
Edo Period (1603–1868)
Tokugawa Ieyasu unified Japan and began the Edo shogunate in 1603, ushering in a period of peace that lasted more than 260 years. The ninja faced a general decline in demand for their services, and some families experienced poverty.
The Shimabara Rebellion
The Shimabara Rebellion of 1637–38 was the last major battle in which Koka ninja played a role. Amakusa Shiro (1621–1638), a young Japanese Christian, led an uprising against the shogunate at Hara Castle, Shimabara (present–day Nagasaki and Kumamoto Prefectures) for its anti-Christian policies. Ten Koka ninja were among the troops sent to stop the rebellion, and their task was to collect information from within the castle. They successfully infiltrated the castle and sabotaged the rebels’ food supply. However, confused by the unfamiliar local dialect, they got caught in the rebels’ trap.
The Koka Koshi
Following the unification of the country under the Tokugawa shogunate in 1603, the ninja faced a general decline in demand for their services, with some families even experiencing poverty.
In 1789, a group called the Koka Koshi (Koka veteran warriors) journeyed to Edo, presenting the Bansenshukai (a compilation of detailed ninja knowledge) to the shogunate with the aim of proving their heritage and professionalism. For their efforts, they received silver to take back to the other ninja families in Koka.
