Some emails received in response to Roberto De Vido's Foreign Agenda column:

Roberto De Vido makes a good point. I've often wondered about the contrast between clean streets and the unwarranted dumping of rubbish and domestic items in rivers or the countryside.

Previously I ascribed it to the uchi-soto [inside-outside] nature of Japanese culture: You don't despoil your own surrounds, but you can do as you like in places unconnected to you, such as in nature.