The tax on a packet of cigarettes in Japan is going up by almost 40%, the biggest rise ever seen there.
The price of the most popular brands is rising on Friday by about 40%, from 300 yen ($US3.60) to 410 yen ($US4.90).
The aim is to encourage smokers to quit. But the BBC reports smokers have been busy stocking up on cigarettes instead.
Japan Tobacco has shipped an extra 12 billion cigarettes, one month's supply, to meet demand.
Family Mart, a chain of convenience stores, reports that sales have nearly doubled in recent weeks.