For Tadashi Yanai, the founder and president of the Uniqlo parent company Fast Retailing, the United States has become a source of both immense optimism and concern.

In recent years, Uniqlo¡¯s affordable, well-made basic clothes have struck a chord, especially with younger American shoppers, fueling a rapid business expansion. The United States is now a pillar of the growth strategy of Japan¡¯s Fast Retailing.

Yanai, 76, came of age in postwar Japan, steeped in American culture. He wore Converse and drew inspiration for Uniqlo from casual-wear brands like Gap. Conquering the U.S. market is also a matter of personal legacy for Yanai, whose Uniqlo empire today comprises more than 2,500 stores globally.