Hidden Architecture in the Ninja’s Home (Part 1)

Ninjas (in Japanese, shinobi) were more than assassins. They were also the spies and undercover agents of medieval Japan. 

When working for others, ninjas were masters of infiltration, stealth, and disguise, but shinobi didn’t employ these techniques only in the service of others. Stealth and concealment were a way of life in shinobi villages, and made their way into the design of ninja homes as well.

During my trip to the Iga Ninja Museum last June, I had the opportunity to tour a replica ninja house, and to see a demonstration of its unique architectural features. Today, I’m sharing a little about the technique of concealed spaces beneath the floor.

Many medieval Japanese homes were built on raised foundations. In shinobi homes (and doubtless other structures influenced by the design), it was common to find two different types of concealed spaces beneath the flooring: weapons caches and concealed spaces for storing money and other valuables.

16A11 Shinobi Floorboard Open (2)


Since many Japanese homes had wooden floors, it was simple to conceal a weapons cache beneath a moveable floorboard:


16A11 Floorboard



More difficult was making the floorboard appear completely normal (read: not loose or wobbly) when the cache was closed.

16A11 Shinobi floor

Shinobi architects perfected techniques for seating moveable floorboards that made them easily mobile in case of need, but neither wobbly nor unstable when walked across.

Another, more advanced technique for creating a hidden space beneath the floor involved concealing the entrance in a doorway, beneath the sliding track that held the door.


For this type of cache, the architect (or the shinobi who made the alterations after the original construction was finished) created a section of doorway track that looked like the rest:

16A11 Iga Ryu

…but could actually be lifted away, either directly or after flipping a hidden switch or panel on the floor.

16A11 Floor Panel Open

Once the track was removed, a hinged section or panel could be lifted, revealing the hidden space beneath. These spaces could be used for storing money, weapons, or even human beings–many were large enough to hide a person (sometimes, more than one) in case one or more of the house’s inhabitants needed to disappear on very short notice.

16A11 Floor Panel w Guide

While hiding spaces like this would not be used to conceal the entire family–someone needed to remain above the floor to replace the track–it could be used to hide a single person fairly efficiently, and was also an ideal place to conceal valuable objects.

Hidden caches and passageways were common in ninja architecture. Some, like the ones in these photos, were designed for use with objects only, but most ninja houses had several places a person could hide as well.

Next Monday, I’ll share some photographs and architectural pointers about the hidden passageways and cubbyholes that featured in many ninja houses (and some samurai houses, too).

Have you ever visited the Ninja Museum in Iga, or another house that featured hidden passageways? Would you like having a hidden cache or hiding-hole in your house?