It was just a regular Friday, but lovers of beerlike beverages found an excuse for another round as the country's major breweries marked down their versions of "happoshu."

In back-to-back moves June 21, four major breweries cut the price of their flagship low malt brews to 135 yen for 350-ml cans, from 145 yen.

The price war, estimated to cost makers tens of billions of yen in profits, is being driven by cutthroat competition in a market largely devoid of brand loyalty.