It’s a news story practically lab-made for social media: an American, Chris O’Neill, has been recruited by a tourist organisation in Japan’s Aichi district to become, in its words, the country's “first salaried, full-time ninja”. So far, so awesome. Only, here’s the thing: the ninja tradition may be total fantasy. We asked Stephen Turnbull, a military historian based at the University Of Leeds specialising in Japan, to separate fact from fiction...

What exactly is a ninja?

“If the ninja have any basis in fact, the following three criteria must be satisfied,” says Turnbull. “One, that a unique corpus of military techniques involving secrecy existed in Japan during the Sengoku Period [c. 1487 - 1603]. Two, that the exercise of these techniques was confined to certain skilled individuals rather than being spread more widely within Japanese society. And three, these skilled practitioners were identified in particular with [the areas] Iga and Kōka, from where they sold their services to others.”

Let's work through those points. Did a unique form of secret warfare ever take place in Japan?

“Secret warfare was not an isolated Japanese speciality, nor was it confined to the Sengoku Period. Undercover operations are to be found throughout Japanese history, and one component of the modern ninja cult has been to exaggerate this fact by crediting certain historical figures with being ninja or 'proto-ninja'. One particularly romantic example of secret activity from the fourteenth century is the account in the Taiheiki of the murder of Homma Saburō by the youth Kumawaka, who escaped by climbing up a bamboo trunk (in itself no mean feat) and allowing it to deposit him in a place of safety. This is a good story that may with complete justification be described as a 'ninja-like assassination', but the boy was not a ninja.”

Was ninjutsu developed by emigrants from Iga-Kōka, as is commonly believed?

“If men from Iga and Kōka acted as mercenaries that alone would make them unique in Japan. [The mercenary] model, which was very common in Medieval Europe, was totally absent from the Japanese scene, although some Japanese warriors did serve as mercenaries overseas. Between 1593 and 1688 Japanese fighting men, most of whom were exiles and many of whom had experience of piracy, were in the service of the kings of Siam and Cambodia, the Spanish colonists in the Philippines and the Dutch East India Company. There is nothing comparable within Japan itself. Rather than preferring such a casual model, the emerging daimyō (warlords) valued loyalty and long-term commitment. The only “swords for hire” within Japan were small groups of desperate rōnin (immortalized forever in the film Seven Samurai), and even they would tend to become quickly integrated into a daimyō’s army.”

Did a warrior elite ever exist at all?

“Practitioners of secret warfare in historical accounts were warriors who operated within the usual command structure of a daimyō’s army. They were elite warriors but not a cult-like warrior elite from a distant province who served as mercenaries.”

So the whole thing’s made up?

“I do not believe that the Iga-Kōka ninja myth or the modern cult that developed from it represent a total fabrication. All invented traditions have a basis in fact, no matter how tenuously the links may be made between the developed tradition and recorded history. In Iga and Kōka there must have been some genuine belief in a unique local expertise that was bolstered by folk memories and old soldiers’ tales, and the best that can be said for their plagiarism of other people’s exploits is that it supports one great ninja stereotype: they were very good at stealing things! Yet even if the Iga-Kōka ninja cult draws upon little more than the manipulation of folk memories and historical records, any tradition that takes shape in about 1620 and continues to the present day is worthy of more attention and respect as a cultural property than is commonly given to other aspects of the samurai tradition. As the Iga and Kōka ninja tradition is older than the 47 Rōnin and even predates bushidō it should not be dismissed but celebrated as Japan’s oldest martial invention and, through its modern cult-like manifestation, as Japan’s greatest martial fantasy.”

Though that would, of course, be exactly what the ninja would want you to think…

All quotes from “The Ninja: An Invented Tradition?” by Stephen Turnbull. Published in The Journal Of Global Initiatives: Policy, Pedagogy, Perspective (Volume 9, Number 1: Interdisciplinary Reflections On Japan, 2014). Stephenturnbull.com