Beef prices are returning to levels last seen before the outbreak of mad cow disease last September, thanks in part to beef eaters ordering more as a way to increase stamina and ward off the oppressive heat, according to industry officials.

On the Metropolitan Wholesale Market in Tokyo, the benchmark price of class-A "wagyu" beef has been rising since the end of the rainy season in late July. It shot up to above 1,800 yen per kg at one point.

That level had not been seen since before the outbreak of mad cow disease, or bovine spongiform encephalopathy, and is well above the record low of 1,100 yen posted in February in the wake of the mad cow scare and a series of beef-labeling scandals.