Japanese clothing chain Uniqlo is opening its first West Coast location as parent Fast Retailing Co. rolls out its plan to open hundreds of stores in the U.S., even as American retailers are retrenching.

The 29,000-square-foot San Francisco store, near where Gap Inc. first opened its doors, heralds more pressure on U.S. retailers already battered by foreign competitors. Uniqlo is also scouting locations in Los Angeles and other California cities, says U.S. Chief Executive Shin Odake.

Uniqlo's three existing U.S. stores all are in New York City. The San Francisco store will open in the fall.

The company has high hopes for the U.S. market, where by 2020 it expects revenue to reach $10 billion, one-fifth of its projected total. For the fiscal year ended Aug. 31, 2011, Fast Retailing's overall sales totaled $10.6 billion.

Executives are considering real estate for flagship stores in Philadelphia, Boston, Chicago, Washington and other major cities as Uniqlo looks to secure locations for 10 to 20 stores by year end, says Mr. Odake. He expects that number to double by the end of next year.