What also rules: running three miles through Ueno Park and then through the streets, watching people coming alive to start the day, and watching the kids heading off to school. (Adding a touch of Vienna Teng:s "Lullabye for a Stormy Night" only improves things.) My favorite was what appeared to be a high school boy on his bike, with his elementary school brother (complete with adorable hat) trotting along beside him.
The rule that drivers need to stay on a particular side of the road is more of a guideline, but in these streets, it kind of has to be.