Ah, yes, I've heard that theory. It goes that Haruko symbolizes America; loud and obnoxious, but strong; whereas Naota symbolizes Japan; shy, indifferent and weak. America had to help Japan grow up and even find its own identity, just as Haruko does the same to Naota in the series.

I don't think it's an "official" interpretation, but it's interesting nonetheless.

>>13: Look at the participation percentages in elections in America and in other parts of the world. Some European and Asian countries rarely get over 40% of the electorate bothering to vote. And I met a Canadian friend who bought the whole "Canadians are more intelligent and worldly" line, but couldn't even tell me how many provinces Canada has.