The Japanese penchant for Americana is not merely a story of economics; it is a matter of style. It has not been unusual for Japanese men to wear the Ivy look in head-to-toe extremes once unthinkable here — say, a blazer, tie, plaid shorts and knee socks. But given the zeal for American designers like Thom Browne and Scott Sternberg of Band of Outsiders, who tinker with old-fashioned Americana (and whose lines are made in the United States and are very popular in Japan), extremism is finally becoming fashionable here.