Japan is one of the world's biggest consumers of seafood. While its consumers are known for paying a premium for high-quality food products, and for setting global food trends, Japan has lagged behind Europe and the United States in adopting policies on traceability and sustainable fisheries.

"I would say awareness has really improved in recent years," Kinzou Matsumoto, general manager in charge of Aeon's seafood merchandising planning, said on Tuesday as the company unveiled an expansion of its eco-certified lineup of seafood to include oysters approved by the Marine Stewardship Council (MSC).

"Right now, certified items make up around 15% of our entire seafood products. Ideally we want to bring it to around 20%," he said, adding that it would soon have enough types of certified fish to assemble assorted sushi packs.

"We want to sell certified sushi to visitors coming to the Olympics, too... and that would have to be by June."

The MSC said Aeon's scale would help expand recognition for sustainable seafood among Japanese consumers, and encourage fisheries.

"A commitment from Aeon is critical in driving change," said MSC's Asia-Pacific regional director Patrick Caleo.

Japanese businesses including beer makers and hotels are making preparations to cater for record numbers of foreign visitors to Japan this summer as Tokyo hosts the Olympic Summer Games beginning in late July.

Kura Sushi, among Japan's largest conveyer belt sushi chains, is opening its biggest branch this week - a store with 272 seats expected to draw 2,000 customers a day.

It forecasts that the number of foreigners visiting its restaurants in Tokyo to rise by about a third compared to a usual year.

Kura Sushi President Kunihiko Tanaka also defended the safety of seafood in Japan, including those from Fukushima, the site of the 2011 nuclear disaster.

Government data shows Fukushima seafood is "absolutely" safe, Tanaka said, adding that Kura Sushi planned to open a restaurant in Fukushima.

South Korea's Olympic committee said in December that it plans to buy radiation detectors and ship homegrown ingredients to Japan for its athletes because of its concerns over food.

(Reporting by Ritsuko Ando and Ju-min Park; Additional reporting by Maki Shiraki; Editing by Christopher Cushing and Susan Fenton)