Ninjutsu Legends: The Amazing Tale of the Iga and Koga Clans!

The Iga and Koga were the most famous ninja families of Japan’s feudal period. These clans protected their way of life through the art of ninjutsu. Let’s take an in-depth look into their origins and lasting influence!

What is ninjutsu?

Ninjutsu was a set of spying and survival skills from old Japan used by ninjas. They were the secret agents back then, focusing on being smart and sneaky instead of just looking for fights. Ninjas had to gather information, stay hidden, and endure tough times. Ninjutsu wasn’t just about fighting but also included sneaking around, disguising, escaping, and even knowing about medicine and the weather.

These ninja skills involved different kinds of martial arts, like hand-to-hand combat, sword fighting, and throwing stars. Ninjas did important secret missions like spying and sabotage, always trying to blend in and sometimes fighting without weapons to avoid getting caught.

Ninjutsu began with mountain hermits who were all about surviving in nature and protecting themselves. Even though we no longer use ninjutsu for spying, its smart, sneaky, and adaptable ways are still taught in some martial arts and self-defense classes today.

Where were Iga and Koga?

Iga and Koga (sometimes called “Koka”) were Japanese provinces between Lake Biwa and Ise Bay. Today, Iga City still exists in Mie Prefecture, and Koga City lies to the north in Shiga Prefecture. They are known to be the birthplace of ninjutsu (忍術). Iga was situated in a large lowland area surrounded by the Nunobiki Mountains.

The Suzuka Mountains formed the border with Koga. Here, people learned to depend on themselves and had many jobs, ranging from samurai to lumberjacks! While the former were landowners, the latter harvested wood to build houses for their fellow villagers.

However, the skills of the mountain priests (yamabushi) probably had the most significant influence on ninjutsu. They lived in the surrounding mountains, surviving in the wilderness. These spiritual hermits spent their days studying nature, skillfully negotiating the rugged terrain as a form of meditation. Not to mention, they jumped from tree to tree in their pursuit of perfection!

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Who were the Iga and Koga Clans?

In time, these village warriors (jizamurai) formed “clans.” They taught their skills to their children, who trained from childhood! The most powerful of these families were the Iga and Koga, who eventually controlled both provinces. They formed the Iga-Koga alliance in 1487 and agreed on rules to defend the region.

It was everyone’s duty to defend their settlements and livelihoods. Even monks and mountain priests joined the battles! By the time the two groups began ignoring orders from the government, they were already a skilled army. There were sometimes feuds between the two families, but they always fought together against invaders.

Why did they feud?

Before the alliance, the two clans had a feud that lasted hundreds of years! It is uncertain what started it, but it may have been competition for space. The rivers in the valleys flooded the few available flat areas, leaving mostly the uneven uplands for growing food and gathering resources. 

There were constant disagreements between the two provinces’ families, land owners, farmers, and villagers. These were not significant battles, but weapons were often used, so castles were built at valley entrances to protect inhabitants. Today, about 800 castle ruins exist where these provinces once existed—one of Japan’s highest concentrations of castles!

What was their influence on ninja history?

Oda Nobunaga finally invaded and defeated the two clans. But the Koga’s strategies to defend their homes made these fighters famous across feudal Japan. And the Iga became known for their ability to attack castles (shirotori). Many ninja from both groups were later hired by daimyo for their unique abilities!

Ninjutsu spread throughout Japan. The Iga helped Tokugawa Ieyasu create his shogunate. They worked as guards inside Edo Castle while the Koga guarded its gates. Members from both families continued to serve various lords for more than one hundred years. They helped win many famous battles like the Siege of Osaka and the Shimabara Rebellion, often outnumbered. They fought on the front lines, snuck into castles, and stole passwords.

You can still witness these two ninja schools today! In Mie prefecture, the Ninja Museum of Igaryu still attracts those who wish to learn more about their beliefs and everyday life. In Shiga prefecture, Koga Ninja Village draws visitors who want to learn about their many techniques. Have you visited these ninja museums before? Do you know of any other such places in Japan? How was the experience? Tell us below!