Shiga: Ninja Secrets Uncovered in Their Hometown

The Yomiuri Shimbun
Toshinobu Watanabe stands next to an old chest of drawers, where he found ancient documents, in the storehouse at the back of his home in Koka, Shiga Prefecture.

KOKA, Shiga — Research on ninja is enjoying a boost in the public and private sectors after cultural properties in Koka, Shiga Prefecture, and Iga, Mie Prefecture, were recognized as Japan Heritage sites, “Shinobi no Sato” (Ninja homelands), in 2017.

The ninja from Koka, among the top regions for ninja training, were called shinobi or Koka-shu and were employed for various battles in the Sengoku warring states period — 15th to 16th centuries — when they excelled in espionage and guerrilla activities.

This is perhaps because of the region’s proximity to Kyoto, the capital of old Japan, which attracted people of diverse occupations. The lumberjacks, carpenters, monks that live in the mountains and others who flocked to Kyoto were valued for their excellent intelligence gathering abilities, craftsmanship, military skills, and religious and medical knowledge.

Descendant of ninjas

Toshinobu Watanabe returned to Koka in 2000 after 37 years of corporate work mainly in Tokyo. He discovered evidence in his childhood home that his ancestors were ninjas.

In an earthen storehouse at the back of his house, Watanabe found 157 ancient documents in an old chest of drawers. The documents contained information on military techniques called ninjutsu and other martial arts, such as iaijutsu (the matial arts of quickly drawing a sword), kajutsu (the art of utilizing gunpowder and fire) and taijutsu (unarmed combat) as well as their genealogy and religious beliefs. These became conclusive evidence that he is a descendant of actual ninjas.

According to a series of documents, the Watanabe family was so skilled in guns and pyrotechnics that they were recruited by the Owari clan in the early Edo period (1603-1867). Owari was a leading domain centered on Nagoya Castle, now the western part of Aichi Prefecture.

Watanabe’s ancestors were part-time ninjas who rode to the castle on horses whenever needed by the clan. Their family’s duty lasted for about 190 years, and even Watanabe’s great-grandfather bore the duty.

It was a secret held within the clan that they were ninjas. Ostensibly as gun instructors, they attended annual shooting drills. In secret, they signed contracts with their lords stating they would do their best through their arts, risk their lives in service, and not tell their parents, children, siblings or close friends about their secret occupation.

They were believed to have usually lived locally as farmers or headmen, while practicing various arts and trying to sneak into other castle towns.

There is a stereotype that ninjas spent all their time in battle using their secret arts. But Watanabe, 82, sees them as mostly ordinary villagers.

“Ninjas were also human beings, as their arts are not such special skills,” he said.

■ Utilized for local tourism

The Yomiuri Shimbun
Visitors view ninja tools that are displayed at the Koka-ryu Real Ninja-kan, in Koka, Shiga Prefecture.

In Koka, the municipality has been focusing on researching and promoting ninja in recent years. The city government aims to help “visualize the ninja.”

A research group was formed in 2015 to examine old documents and artifacts. The group Koka-ryu Ninja Finders, headed by famous historian Michifumi Isoda, published three books in fiscal 2017-19, including texts from the Watanabe family’s documents, which were printed in their original forms along with an interpreted version.

In September 2020, the city government opened the tourism information center Koka-ryu Real Ninja-kan (House of Koka school real ninja). Visitors can experience “Goton no Jutsu” — five ninja techniques used to hide from enemies using five elements. The city government also plans to use old houses nearby as a ninja school.