Japanese consumers are taking the news of the first case of mad cow disease in the United States with relative calm, with restaurants and supermarkets reporting none of the tumbling sales they experienced two years ago.

"There has been no sharp sales drop so far. The sales are surprisingly normal," said a spokesman at Yoshinoya D&C Co., which runs "gyudon" beef-bowl restaurants.

Importing 99 percent of its beef from the U.S., the chain was initially considered one of the hardest hit.