As I often write here, each nation has a unique "national character" which the Japanese call kokumin-sei. Part of Japan's national character is to have a very neutral attitude when it comes to patriotism, and many everyday features of life in America -- reciting the Pledge of Allegiance, remembering Veteran's Day or shedding a tear at Arlington National Cemetery -- are totally absent here. There are several reasons why the average Japanese finds it improper to show a reasonable love of their own country, including awareness of Japan's nationalistic past -- current-day North Korea is a stark reminder of what Japan was 70 years ago -- and the sad tendency for the Japanese flag to be associated with silly right-wingers, who drive around in loudspeaker cars playing WWII-era military songs and, somewhat more awesomely, the Space Battleship Yamato theme song. One country that doesn't lack for patriotism is South Korea, whose citizens recently brought the White House website down with petitions asking them to support changing the Sea of Japan to the name they prefer, the East Sea, despite the fact that former name has been in use by the majority of world nations (including China) since 1602.
Flamboyant right-wingers aside, Japanese lack patriotism.