Isshi Soden and a Page from the Koka Tradition

Today I will touch upon the topic regarding a traditional practice called Isshi Soden1. This is a common word generally associated with the world of Koryu Budo, or Classical Martial arts. For those new to this, Isshi Soden is a method or process that involves passing down of a specific martial tradition within a family or group to a younger individual. It is not limited to only the martial arts world; interestingly, other fields of artistic skills and services are found to incorporate this as well, such as chado (tea ceremony)2 and shodo (calligraphy)3. It was a process used considerably in Japan’s past, but has lost its popularity immensely in modern times. For now, let’s look into Isshi Soden and how it is utilized, primarily through an old documentation connected to the renowned Koka4 tradition.


There are written proof of families and groups that practiced the use of Isshi Soden. For example, there is antique scroll called “Ninjutsu Ougi Den5“, which comes from the Mochizuki family. Here’s an entry from the scroll, followed by an English interpretation done by myself.

A section from the scroll “Ninjutsu Ougi Den”.


“To our descendants do we pass down the ancient craft of incendiaries. If there is no one to pass on to, this skill will turn useless. This process is called Isshi Soden (passing on knowledge to a successor). Outside of this process, it is arguable that the knowledge (of Koka ryu) can be bought.”

The contents of “Ninjutsu Ougi Den” relate to the spirit and dedication one must have as being of the Koka tradition, and what it takes to pass on the secret trade used by those specializing in Koka ryu. The line above is a representation of this belief. The scroll was written by Mochizuki Shigeie6, the grandson of Koka Saburo Kaneie7, who’s said to have started this Mochizuki family line in Shinano no Kuni (Shinano Province)8. The Mochizuki family were an influential warrior family amongst those of the Koka tradition, who were primarily active during medieval Japan.


Koka ryu is a martial system that specializes in various methods of combat, especially in shinobi-no-jutsu9. Developed in the mountainous region of Koka in Omi no Kuni (Omi Province)10, Koka ryu was a system many families who lived in that region were versed in. Unlike conventional martial systems, Koka ryu focused more on unconventional,  guerrilla warfare-like tactics, including spying, sabotage, and arson. These skills were very critical during the medieval period in Japan for many daimyo, or warlords, who wished to keep track of and get the upperhand on the opposition.

Those reputed in specializing in shinobi-no-jutsu could gain employment for special tasks the average warrior couldn’t handle, even if for a short time. Due to the nature of the times and what the skills entailed, the knowledge of Koka ryu was well guarded and rarely shared to anyone outside the area of Koka.


Koka ryu encompassed many different families that banded together to ensure their survival, and formed organized groups such as “Kokagun Chuusou11“. The knowledge of Koka ryu was treated like a special trade, and taught amongst family members. This is where Isshi Soden comes in play, for it ensures that inheritance of each particular style of Koka ryu is passed down within the family or group. The new inheritor not only gains leading role, but everything key to maintain ownership and preserve of the system (including secrets and teachings in the form of poems and sutras not shared to anyone else) is transferred in its entirety.

Generally, Isshi Soden specifies a martial system being passed down to one child of the current headmaster (generally a boy), even if there are multiple children within the family. However, it is not limited to this, and can involve passing inheritance to one who is not blood-related. In fact, it has been recorded in documents from Japan where some headmasters would go as far as to adopting an individual as their own, and from there pass on their knowledge to that one person. Case in point, in Mamiya Hyoemon’s book “Budo Shiroishi no Eiyuu”, Takagi Oriemon inherited the kahoujutsu (skills utilizing artillery) of the Muraoka family from Hyobu Muraoka, in absence of Hyobu’s son whom he hadn’t seen in a few decades12.

Certain traits are a requirement for an individual to be chosen as an inheritor under Isshi Soden. Some of these have to be qualities that are naturally there, while others may have to be groomed. In regards to the Ninjutsu Ougi Den, it is advised that the next in line should fit a particular criteria. Here is the line from the scroll, followed by my interpretation in English:


“…one must wholeheartedly have full devotion in their mind, possess no doubts, bear this responsibility for a very long time, and to never abandon faith. The (next) successor must be properly instructed (to handle the duties his role calls for)….”

From this, we can understand how important it was to properly choose the next successor. It was not a responsibility to take lightly.


Martial systems that were dependent on Isshi Soden treated this as a means to survival. Since Japan was faced with much turmoil before peaceful times set in during the Tokugawa Shogunate from the early 1600s onward, many warrior families had a reason to be active, striving to keep their martial systems intact. Koka ryu is no different. However, once the need for specialists of shinobi-no-jutsu was no longer high in demand within the unified Japan, many families struggled to keep their trade alive. Employment as spies and the like was no longer feasible, so some had to settle for guard work, or positions similar to police work. One big effort was even made by Fujibayashi Samuji Yasutake, a descendant of the Fujibayashi family known for their role in shinobi activities. He compiled as much info he could collect on the secret techniques and methodology of the shinobi, and proposed it to the Shogunate in a large documentation called “Bansenshukai13” around 1676, hoping to rekindle interests in their worth. Unfortunately, this was to no avail.

A picture of Fujita Seiko, 14th headmaster of Koka ryu Ninjutsu Wada Ha. From Wikipedia.

Much of the knowledge and skills of Koka ryu have been discontinued and lost. Certain special terminologies found in the few documents remaining are difficult to interpret, due to their meanings being obscured and forgotten. Some of the reasons behind this include the last successors no longer seeing any purpose to pass on a system viewed unfit in a society that was rapidly changing, as well as not finding a suitable inheritor amongst their children. Another point, Koka ryu’s doors were not open for public admission like other martial systems that may specialize in conventional means for combat like kenjutsu or sojutsu, thus there was no chance for it to spread and evolve.

Interestingly, Fujita Seiko (1898 – 1966), who inherited his family’s ninjutsu system from his grandfather, did not completely feel the same way as other headmasters of Koka ryu.  He states in his book “Ninjutsu Hiroku14” how he believes ninjutsu still has purpose, despite the view of ninjutsu not having much use in modern times. Aspects such as the spirituality and applications of ninjutsu would prove useful, as well as be a good means of self defense for people and the country (Japan) against threats15. Despite his views,  Fujita Seiko did not pass down his style called Koka ryu Ninjutsu Wada Ha16, unfortunately. Presently, his system remains unknown to the public.


This wraps up our discussion on Isshi Soden. As pointed out, practice of Isshi Soden can be beneficial, as long as it fits the purpose and the environment. It was seen as valuable, as described in the scroll belonging to the Koka tradition. Thanks for reading and stay tuned for more discussions.

1) 一子相伝. This methodology of passing down inheritance is similar to 父子相伝 Fushi Soden.

2) 茶道

3) 書道

4) 甲賀. “Koka” is considered the correct pronunciation in recent times. A more common and popular way to pronounce this is “Koga”.

5) 忍術應義傅.

6) 望月重家

7) 甲賀三郎兼家. Also known as Mochizuki Saburo Kaneie (望月三郎兼家).

8) 信濃国. Present day Nagano Prefecture.

9) 忍びの術, also can be written as 忍術. Older term for the now modernized term ninjutsu, which is written with the same characters.

10) 近江国. Present day Shiga Prefecture.

11) 甲賀郡中惣. The Kokagun Chuusou was created by a collection of several families from the Koka region that united together as a unit, with some sharing the same surname, . They banded together in preparation to defend themselves around the mid-late 1500s when Oda Nobunaga, an uprising powerful warlord, set out to invade and annihilate the areas of Koka and Iga (a neighboring area), which both operated along their own rules. 

12) A clearer recount of the tale goes as follows: Takagi Oriemon set out on a years-long musha shugyo (warrior’s journey to hone one’s skills) throughout Japan during the 1600s. Early in his trip he encounters 2 monks, and travels with them for awhile. One of them, who duels with a kusarigama, goes by the warrior name of Tetsudo. Oriemon develops good relations with the 2 monks, before finally all 3 set off on their separate ways. A few years later, as Oriemon was climbing up a Mountain called, Takayama, he encountered an old man named Muraoka Hyobu, who was a skilled marksman. Oriemon assisted in taking down a wild boar while Hyobu was hunting, and carried it for the old man back to his home. Staying for dinner, Oriemon conversed with Hyobu and his wife, where it came out that they were the parents of Tetsudo, whom they hadn’t seen for around 20 years. Moved that Oriemon could bring good news about his lost son, Hyobu decided to pass down complete knowledge of the kahoujutsu unique to the Muraoka family to him. He did so as Oriemon had a strong, yet likeable quality to him that made him trust worthy, as well as for Oriemon to someday initiate Tetsudo into the family tradition in place of Hyobu.

For those interested, you can read more about this and other tales regarding Takagi Oriemon in “Takagi Oriemon: Budo Hero of Shiroishi”, a translation project by those of the Jinenkan Honbu Dojo.

13) 万川集海. Also pronounced as “Mansenshuukai”.

14) 忍術秘録

15) Fujita Seiko makes this statement in “Ninjutsu Hiroku” on page 14, starting from line 8 of the original book. The statement (in Japanese) goes as follows:


16) 甲賀流忍術和田派

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