The bus is one of the best places for observing Japan. It's different from the train, where people pack in and do "gaman" till they get to their destination.
On the train, you might catch a glimpse out the window of people riding bicycles through rice fields on their way to work, a patch of blooming flowers or a group of elementary-school children walking to school. But when you look out the window of the bus, you see humanity up close.
You see that the elementary-school children are huddled together examining a caterpillar they had scooped up from the sidewalk. You imagine that every child has observed a caterpillar, spoken to a crow, and splashed through a puddle before arriving at school at 8 a.m. You see that the flowers are blooming in decrepit pots. Those bicycles have arrived in town and are now resonating "cha-ching, cha-ching" while running down pedestrians upon the rider's realization he is going to be late for work.