When writing the Shinobi Mysteries, I try to include as many historically accurate details as possible, and to include at least a few neat facts most readers might not know.
In order to keep the stories moving, I often can’t call attention to these details in the books themselves, but I love being able to share them here on the blog.
The fiction: In the opening pages of Blade of the Samurai, my ninja detective, Hiro Hattori, uses a squeaky floorboard as an alarm to alert him to an intruder outside the house.
The fact: Yes, this could have happened.
In medieval Japan, some castles (and other buildings, too) were constructed with special floors that made a squeaking or chirping sound to alert the residents to intruders (or anyone else) walking across the floorboards.
Modern myths claim these floors were designed to prevent shinobi (aka “ninja”) assassins from harming the occupants. In reality, that was probably only part of the reason. Wealthy samurai faced many threats in medieval Japan, including thieves, sneaky guests, and attacks by a range of enemies, of whom shinobi were only one.
Squeaking floors could alert a host to guests moving around in the night, to servants in places they didn’t belong, or even a teenager sneaking out for clandestine adventures, as well as assassins and other lethal threats.
These special floors were called uguisubari, which translates “nightingale floors,” because of the chirping noise they made. Architecturally, the floors were constructed with nails positioned to rub against a metal jacket or clamp when someone or something placed pressure on the boards.
In modern times, we often spend great time and money to ensure that hardwood floors are properly “de-squeaked.” When I first learned about nightingale floors, in college, I was fascinated by the ingenuity of medieval Japanese architects. Finding a way to create “alarms” without the modern bells and whistles (literally and figuratively) has always struck me as an extremely clever use of architectural design.
When writing Blade of the Samurai, I needed a way for Hiro to realize an intruder was approaching Father Mateo’s house at night. My thoughts immediately went to the nightingale floors, and I knew they would be an intriguing–and historically accurate–answer.
If you’d like to see how the scene played out, you can read the first six chapters of Blade of the Samurai here. My publisher’s free sample just happens to contain that scene with the nightingale floor!