Oil companies are aggressively building self-service gas stations combined with convenience stores, coffee shops and other stores across the country.

Though the number of self-service stations is still small, at about 3,300, accounting for only about 6 percent of the total, their gasoline sales account for 20 percent of the total, an official of the Oil Information Center said.

The presence of food retailers and the like at gas stations is not uncommon in North America and Western Europe, but the concept is still in its infancy in Japan.