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The Modern Guide to the Ancient Text: Book of Ninja (Part 2: Yo-jutsu)

The Modern Guide to the Ancient Text Book of Ninja (Part 2 Yo-jutsu)

A Japanese lord passes through life thinking he knows the people around him, until the night his faithful vassal ambushes him and takes his life without warning.

How long he’d lived, unaware that his enemies were targeting him with yo-jutsu: the skill of hiding in plain sight. If it had been through in-jutsu or the art of stealing in without being seen, he might have been spared the pain of betrayal.

Yo-jutsu is a type of espionage that requires clever disguise, wise strategizing and subtle communication.

The Undercover Ninja

There were many types of undercover agents one could use or become for yo-jutsu. Here are just a few:

An anaushi agent lives in in a private house near the enemy and is on close terms with him. The agent expresses a desire to serve him when the time comes and becomes a double agent.

A kunoichi agent is a woman. Since women were thought to be dumb and inferior at the time, they could infiltrate deeper, with less suspicion and get closer to the enemy than men to accomplish their goal.

A worm agent or minomushi is a double agent who pretends to serve the enemy but is on your side. He becomes like a “parasite” in the enemy’s “stomach” to gather information and carry out plans.

Becoming an Agent

To become an undercover ninja, hostages such as fathers, wives and/ or children needed to be handed over to the employer. An oath of loyalty had to be sworn and signed as well.

Sometimes, to become a double agent, a ninja would hand over a fake wife and child and pretty much swear a false oath. So, this method was not entirely fool-proof.

How to Communicate with Your Agent

Once the agent is in, you need to communicate with them through a liaison. This liaison should disguise himself a monk or merchant who discusses information with the agent and reports back to you.

Skills of Disguise

Learn the hairstyles, customs, dialects, languages and topography of the place you plan to infiltrate. If you’re masquerading as a particular profession, learn to be good at that profession’s skills.

Double-Crossing Skills

Jokei no jutsu: The skill of following the enemy’s strategy like a shadow. If you see them planning something, join in to gain information and sabotage them!

The invisible mantle: You have a kunoichi send for a wooden chest. It should contain clothes on top and a secret compartment with a ninja in it on the bottom.

Shikyu no jutsu “relaxing your bow”: Look like you’ll give in when captured, while actually becoming a double agent. When they ask for hostages or an oath, make an excuse or fake it.

Yamabiko no jutsu “the art of echoes”: Faking a crime against your side so that the enemy believes you to be trustworthy.


Yo-jutsu is a truly fascinating study of ninja history! I hope you’ve enjoyed learning about this art of espionage as much as I have.

About Kevin Miles

Kevin started Kage Ninja Gear in 2009 and still runs it to this day. When asked about his company, he proudly states: “We do one thing and one thing only at Kage…we make kick-ass Ninja Uniforms!”

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