Foreword

In this exhibition room, we introduce our activities of "the Koka-ryu Ninja Research Team-Ninja Finders" and the history of Koka-ryu ninja research etc. "The Koka-ryu Ninja" is a world-famous historical and cultural heritage, as evidenced by the story of " Ninja Village Iga and Koka" that makes us feel their reality being certified as a Japan Heritage. However, the true nature is still shrouded in many mysteries. We are dedicated to unraveling these mysteries and spreading the reality of ninjas to the world, proceeding with investigation and research day and night based on historical materials remained in Koka region.


Koka is characterized by the fact that historical materials related to ninjas are carefully preserved and passed down by the descendants of ninjas who remain in this area, and there is still a wealth of resources left today. Just as our predecessors did, we are committed to research and investigation utilizing local materials, consistently pursuing an authentic image of ninjas.


In this exhibition room, there are three themes on display:
1. Introduction of ancient documents, including those of the ninja descendant Watanabe Toshinobu family (the ninja family from the Owari domain), which triggered recent full-scale research and investigation into Koka-ryu ninjas, as well as related materials left in the region 2. Introduction of the early accumulated results by researchers living in Koka and the history of research
3. Regular updates and sharing of introduced achievements and information including new research and findings etc.


The full-scale research and investigation of Koka-ryu ninjas by the research team has just begun and there are still many challenges ahead. Therefore, we hope this exhibition room will serve as a hub for not only our Ninja Research Team but also the Koka-ryu Ninjutsu Research Association, various local history societies etc. in Koka city and researchers and individuals with great interests from various places who aspire to study Koka-ryu ninjas to bring together to exchange and disseminate wisdom and information. We hope you will touch upon the reality of Koka-ryu ninjas here and enhance your "ninja image". We would be delighted if this contributes to convey the true nature of Japan’s world-renowned ninja culture to more people.

 Koka-ryu Ninja Research Team

Official Name : "Koka-ryu Ninja Research Team - Ninja Finders-" An organization that investigates various "aspects" related to ninjas in the land of Koka, renowned as a ninja village The team leader is Mr. Michifumi Isoda (Professor at International Research Center for Japanese Studies) and the deputy team leader is Mr. Eiji Hatanaka (Professor at Kyoto City University of Arts).


The Koka-ryu ninjas have often been discussed based on their image alone. To uncover the "reality" hidden behind or beneath this image, we are currently exploring and investigating numerous ancient documents and ruins that remain in Koka. We are unearthing ninja materials that have been dormant in the region and meticulously investigating and researching them. Our research activities aim to give back to the society through lectures and the publication of historical collections. Our approach is characterized by considering the Koka-ryu ninjas from the perspective of local materials.


Furthermore, this research team also plays a role in making Koka city’s leading policy titled "the Ninja Utilization Tourism Strategy Project" more concrete which has been undertaken since fiscal year 2015 aiming for the "visualization" of Koka-ryu ninjas.

What is Shinobi in Koka?

We casually use and hear the words like "ninja" and "Koka-ryu ninja". However, what they signify is quite vague. It is actually difficult to distinguish between "ninja" and "Koka ninja" and to explain them in concrete. Although it remains a subject of ongoing research for now, we would like to consider the "Koka ninjas" who were active during the Warring States period as follows.


The Koka-ryu ninjas, known as ninja groups called "Kokamono" or "Kokashu" were already famous early on that played an active role in numerous wars during the Warring States period, such as the Chokyo Rebellion, the Udo Battle, and the Shimabara Rebellion. It is believed that there was an important background to this reputation apart from military achievements.


It is characterized that in the Koka region during the Warring States period, there were many people engaged in various kinds of professions. These included the "Kokashu" who also worked as mercenaries, the "Soma" who maintained and harvested rich forest resources, the "Daiku" who processed these materials into building supplies and constructed buildings, and the "Shugen" (mountain ascetics) who wandered across the country from their base at the sacred Mount Hando in Koka. These people lived together, accumulating skills and knowledge. Naturally, they interacted as residents of the same region. As a whole, Koka can be seen as a place where military skills, craftsmanship, religious knowledge, the ability to gather information from distant places, and knowledge of medicinal herbs from the mountains and fields were all present. It was a gathering place for such people with diverse skills or knowledge who could play active parts outside of Koka.”


During the Edo period, many served the Shogunate and feudal lords of various places as “Koka warriors” due to their reputation. This was essentially because of the actual skills and knowledge accumulated in Koka backed by achievements from the Warring States period. In other words, “Koka-ryu ninja” is a collective term for various elements nurtured in Koka and in fact they are also familiar.

“Owari Domain Ninja Officials   "The Watanabe Toshinobu Family Document"

"The Watanabe Toshinobu Family Documents”: This important collection of ancient documents gave Koka city the opportunity to engage in a full-scale investigation and research into Koka ninja. It includes a total of 157 items. The collection contains many military strategy books including historical materials that show the existence of ninjas and ninjutsu books from the second year of Manji to the third year of Taisho (1659-1914).


The Watanabe family who passed down this collection of ancient documents were members of "the Koka Five”, ninjas(incognito officers) employed by the Owari-Nagoya domain, one of the three Tokugawa families during the Edo period. According to the family tradition, the first head of the family, Hisatsuna, moved from Settsu province (part of present-day Osaka prefecture) to Sugitani village in Koka (present-day Sugitani Konan town Koka city) in the 15th year of Tensho (1587). Afterwards the eighth head of the family, Toshimitsu was summoned by the Owari Tokugawa family in the 7th year of Enpo (1679) and served as "a ninja official" while residing in Sugitani village for generations until the end of the Edo period.


"The Watanabe Family Documents” hold great value in that they were historical materials in those days indicating the existence of Koka-ryu ninjas which have been directly handed down at a descendant’s house within Koka city. Previously, due to the lack of reliable historical resources we had no choice but to understand Koka-ryu ninjas ambiguously. However, based on these ancient documents, it has become possible to conduct research and uncover their more realistic figures.


In Koka city, a report summarizing the survey results of "The Watanabe Toshinobu Family Documents” was published in 2017. Considering its value, it has been used as a model case to proceed with the investigation of related materials both inside and outside the city.

Future of Research Team Activities

The research team inspired by "The Watanabe Toshinobu Family Documents” has continued field research and studies centering on documentary materials. These include a ninjutsu book taught by Kimura Okunosuke, the head of the Koka Five including the Watanabe family under the Owari domain, to his disciples, a collection of ancient documents from Okunosuke’s ancestral home and ancient documents passed down in the Ueno Tamaoki family who served as Koka ninjas under the Izumi Kishiwada domain. Several reports have been published based on these investigations.


Although we have not yet reached a complete understanding, through these activities the figure of the real Koka-ryu ninjas who live rooted in the local communities serving as officials as well, is becoming clear. This should be also likely to lead to a clearer understanding and dissemination of the true nature of ninjas worldwide, including not only the Koka-ryu ninja but also the Iga-ryu ninja which could be rival and indeed all "ninjas".


In the future, the research team’s activities are expected to expand further but we believe that more reliable methods based on historical materials and culture from the Koka region should be used. This policy would be effective when we consider ninjas other than Koka-ryu ninjas as well. We aim to gradually uncover the “real ninjas” based on solid evidence, moving away from preceding the conventional ninjas image.

Regular Contract(Regarding Compounded Medicine Sales)

This is a historical document passed down to the Kimura family, the ancestral home of Kimura Okunosuke, the head of the Koka ninja of the Owari domain. The document details a contract involving Okunosuke’s nephew who was a yamabushi (mountain ascetic) and the sale of medicine he "compounded". The contract stipulates that two "Uriko"(salesmen) would sell the medicine in various regions and that the sales would be settled every July and December. Koka is famous as a “town of medicine” and this document is one of the oldest examples known in Koka city that we can understand the relationship between pharmaceuticals and patent medicine. The Kimura family also passes down documents related to the Koka ninja showing that “medicine” an essential element of ninja activities was manufactured and sold on consignment in Koka from an early stage. This document is a valuable piece of evidence of this practice.

Jitoku-ryu Kajutsu Mokuroku(Self-complacency Fire Art Inventory) 

The Watanabe family is known for transmitting military treatises of “artillery" including not only muskets but also large guns, fire arrows, bullets and gunpowder and shooting techniques. Mastery of these artillery skills was a common element among Koka ninjas who served under the shogunate or local lords in various places and might be considered to be one of the conditions for being a Koka ninja. In addition to this, the Watanabe family also possessed a book about knowledge on handling fire like smoke signals. This kind of historical record coincides with the description in the famous ninja book, "Bansenshukai", which states that "The essence of ninjutsu lies in the use of firearms".

■Shinobu -sho(Ninja Book)（These details are not generally available to the public)

The Bansenshukai is a secret book of ninjutsu written by Fujibayashi Yasutake who based on the border between Iga and Koka countries, where Iga and Koka-ryu ninjutsu are compiled. The Ninjutsu Ogiden has been passed down in the ninja Mochizuki family, unraveling the origins of ninjutsu related to Prince Shotoku. Historical materials of Koka ninjas who served Owari domain during the Edo period remain in the Watanabe family. These documents allow us to understand how Koka-ryu ninjas excelled in pyrotechnics and military treatises.



■Koka City Designated Cultural Property　　Bansenshukai

The secret book of ninjutsu passed down in the Ohara Kazuma family in Koka has been designated as a cultural property by Koka city. It was written in the 4th year of Enpo (1676) and is said to be a compilation representing various schools of ninjutsu from Iga and Koka judging from the meaning that "Gathering ten thousand rivers to form an ocean”. This includes detailed explanations on topics ranging from the mindset required for being a ninja to astronomy, techniques for Yang Nin(visible) and Yin Nin(hidden) ninjutsu, methods for creating and utilizing tools, as well as weapons using gunpowder.



■Ninjutsu Ogiden

This is a ninjutsu book from the former Mochizuki family residence of the Shugendo practitioners in Ryuboushi, Konan town. It incorporates the legend of Aburahi Daimyojin and is a scroll which explains the mindset and origins of ninjutsu in classical Chinese characters. The term “Ogi” is believed to be derived from the phrase in the text meaning "Life responds to righteousness".



■The Watanabe Family Ninja Historical Materials

This is a historical document passed down through the Watanabe family in Sugitani, Konan town who served as "ninja officials" for the Tokugawa family of the Owari domain during the Edo period. It includes 17 ninja-related historical documents such as a pledge document submitted when they were serving as shinobi(ninja) and techniques related to fire with gunpowder, medicine preparation and curses.

What Is Kanrin Seiyo?

● Official Name: "Military Law Kanrin Seiyo Middle Volume"
● Era: Copy from the 5th year of Enkyō (1748)
● Size: Booklet measuring 14cm long by 20cm wide
● Page Count: 40 pages (20 leaves)
● Character: A manuscript of the ninjutsu book "Kanrin Seiyo" which became the basis for the famous ninja book "Bansenshukai"
● Content: 50 articles on techniques related to infiltration and combat, movement in the darkness, various ninja tools… all of which are considered to be relatively old techniques
● Location: Discovered at a facility in Katsuragi district, Konan town, Koka city
● Other: Both the upper and lower volumes are undiscovered. Author is unknown.


1 Discovery of Ninjutsu Book! Winter In the 3rd year of Reiwa(2021)　Mr. Takamasa Fukushima (Koka City Local Revitalization Cooperation Team)obtained information about a ninjutsu book in Katsuragi district. Together with a local resident, they investigated a facility in Katsuragi and discovered the ninjutsu book “Gunpo Kanrin Seiyo Middle Volume”. 2 Professors Michifumi Isoda and Yuji Yamada Collaborated! In the morning of June 19 in the 4th year of Reiwa 4(2022) Professors Michifumi Isoda(Head of Koka-ryu Ninja Research Team) and Yuji Yamada(Deputy Director of the International Ninja Research Center) conducted an on-site verification in Katsuragi. At the press conference following the investigation, a large number of reporters including TV and newspapers etc. flocked to the venue and it attracted significant media attention. 3. Future Plans… The discovered volume is the middle one. The search for the upper and lower volumes continues within the city. Additionally, a broad investigation of remaining ninjutsu books and related materials in the city is ongoing.

Koka Ninjutsu Museum (Koka Ninja Village)

Koka Ninja Village is a collection of Ninja Museum, a house filled with contraptions and ninja star throwing area spreading over a large area, resembling the atmosphere of the old -fashioned hidden village of long ago. You can also experience ninja training. The former Okada family standing in the village was relocated private house from Oki in Koka town and you can see ninja tools exhibited at Ninja Museum. The former Mochizuki family residence was relocated from Koji in Konan town with the mezzanine or hidden staircase and this family was related to medicine, The former Fujibayashi family is an edited family house for "Bansenshukai" which is a secret book of Ninjutsu and it is opened to the public as trick house.

Medicine of Koka

Koka is a region known for its thriving pharmaceuticals and patent medicine industry. The origin of the medicine-selling industry is said to date back to when mountain ascetics from Mt. Hando carried medicines as they worshipped across the country for religious purposes. Within Koka and Iga ninjutsu, there are many descriptions related to medicinal herbs, including making gunpowder by mixing saltpeter with various medicines as well as recipes for emergency food such as kikatsugan(hunger-satisfying pills) and hyorogan(military ration pills). These reflect the application of pharmaceutical skills and knowledge, which led to the origin of today’s placement medicine selling.

Ninjutsu Ogiden

This document is a ninjutsu book that has been passed down through the Mochizuki family in Ryuboushi, Konan town where this museum is located. It bears the signature and Kao(written seal mark) of "Koka Saburo Kaneie" who is described as a descendant of Mochizuki Shigeie. Written in classical Chinese characters (kanbun), it records the spirituality of ninjutsu and its foundation lies within "Aburahi Daimyojin Engi" which narrates the origins of Koka chief shrine - Aburahi shrine. The latter part contains the content in common with other ninja book called "Bansenshukai" and the Watanabe family’s ninjutsu books, indicating this is a historical material with the possibility that knowledge and skills related to ninjutsu were indeed widely permeated within Koka. Additionally, an endnote reveals that the content of this material was submitted to Takenaka Hanbei, a general serving under the Oda family, but further details remain unknown.

The Meibun no Koto(the Most Important Duty of Ninja Officials)

This is a copy of a pledge document submitted by the Watanabe family to the Owari domain when they tried to fulfill the duty of ninja officials, This includes three pledges under the names of gods and Buddha. :1. To make the best and sacrifice the life to serve the Shogunate 2. To have comrades serve as substitutes in case of illness 3. Not to disclose information to even close relatives or friends The document mentions deified entities such as "Marishisonten" along with the god of war. "Aburahidaimyojin" representing Koka which is characteristic of Koka ninjas. The addressee "Kimura Iemon" is noted as the head of the Owari domain’s Koka ninjas. This document not only serves to prove existence of Koka ninjas during the Edo period but also is a valuable material passed down no other than to Koka and it is connected with current investigation and research activities on Koka-ryu ninjas."

The Koka Koshi ( a group of local warriors from Koka) Hoko Gansho( a petition to secure positions within the shogunate)

This document is a petition listed by the military service records shared by a group of local warriors from Koka called "Koka Koshi" who submitted the ninjutsu manual “Mansenshukai" to the Edo Shogunate. This petition was intended to serve as a stepping stone for their official appointment by the Shogunate. Such documents are often found in the Koka city area. Many of these documents detail the military achievements of the Koka group who actually joined from "the Battle of Magari" in the first year of Chokyo(1487) to "the Shimabara Rebellion" in the 14th year of Kanei(1637), reflecting the consciousness of the Koka Koshi well. These records later came to be talked about as part of the lore of Koka-ryu ninjas. The document exhibited here was passed down through the Ueno Tamaki family who was a member of Koka Koshi and were deeply involved in managing the Koka chief shrine - Aburahi shrine in Koka.