Today we’re talking tetsubishi (aka “makibishi“).
In English, we call them “caltrops.”
Whether you refer to them by their English or Japanese names, these small, spiked objects served to slow down pursuers and sometimes to alert defenders to the presence of spies or other invaders. One of the simplest designs consists of two metal wires sharpened on either end and twisted around one another to form an “X” with the arms all pointing in different directions. When laid on the ground or a floor, at least one spike always points upward, ready to pierce an unsuspecting foot, hoof, or paw.
Shinobi (more commonly known in the West as “ninjas”) often carried tetsubishi and employed them for a variety of purposes. A handful scattered across a floor could slow down a careless pursuer. Strategically placed, they could lame an adversary or distract him long enough for the ninja to attack or escape. They could also be thrown like a shuriken for attack or defense.
Anyone who’s ever stepped on a Lego brick in the middle of the night knows exactly how this works – and now you even have something more child friendly to yell:
Oh, TETSUBISHI!
It sounds dirty, but nobody will wash your mouth out with soap for this one!