[gshrikant]

Not sure about the accuracy of this (or even the original source) but interesting tidbit from what I've read was that driving on the left side of the road is a remnant of British colonial times which lives on in the modern Commonwealth nations (Australia, India etc.).

[rjsw]

Japan was never a British colony though.

[ksec]

Most country switch to Right side of the road because they hated the Brits. Japan uses the left side of the road because that is simply the right UX.

[Stratoscope]

What makes driving on the left "simply the right UX?"

I would have guessed it is arbitrary, but you may know something I don't. So I'm curious to learn about it.