Japan’s top four convenience store operators all saw sales grow in May – a first since July 2004.

Top chain operator Seven & I Holdings Co, which owns the Seven-Eleven stores in Japan, saw sales rise 3-4%, while Lawson and FamilyMart each saw existing-store sales jump more than 5%. Circle K Sunkus managed a 0.3% increase.

The resurgence of the category has been attributed to a change in the way some people buy tobacco and continued hikes in fuel and restaurant prices. Convenience outlets have reported a rise in the popularity of boxed lunches and other convenience store food as consumers tighten their belts amid rising food and fuel prices.

In the Hokkaido and Tohoku areas of Japan, increased sales were marked down to people going to stores to purchase tobacco instead as age-verifying smart cards were introduced in May to prevent sales to minors at tobacco vending machines.