This is the season when Japanese TV is filled with historical dramas. Lots of kimono and flashing swords!
In Japanese culture, there is a respectful attitude toward swords. Not everyone could have one, and those who were entitled followed certain rules. One of the rules was to use the sword only with the right hand. To do this with maximum efficiency, the sword had to hang from the left side of the body. This makes sense, of course.
Did you know that swords are the reason that, in Japan, traffic flows along the left side of the road? Think about it.
One of the other rules concerning Japanese swords is that no one but the sword's rightful owner has the right to touch it. Not even by accident. Samurai were entitled to cut down anyone who--deliberately or accidentally--touched the sword.
Picture this.
Here comes a Samurai, swaggering down the road, sword swinging from his side. Someone walks past the Samurai on the sword side and accidentally brushes the sword. Sayonara, unlucky blunderer, whether man, woman or child! To avoid accidents, another rule came into play: sword-carrying samurai kept the sword on the outside of the road, away from oncoming traffic.
Voila! The "traffic flows on the left side of the road" rule is born.