Some world leaders are missing the 8 August opening ceremony amid international concern over China's human rights record.
Germany's Angela Merkel is not attending and UK Prime Minister Gordon Brown will be in Beijing for the closing ceremony only.
French President Nicolas Sarkozy says his attendance depends on progress in dialogue between Beijing and the Tibetan government-in-exile. President Bush said on Sunday that skipping the event would be an "affront" to the Chinese people.
Japan has spent a record sum of money and deployed about 20,000 police to seal off the summit at the remote lakeside resort of Toyako.
Hundreds of protesters have again marched through Sapporo, the city closest to the venue, to demand G8 leaders take action on global warming, poverty and rising food prices.
The demonstration, which followed a similar protest on Saturday, was heavily policed and ended peacefully.
Violent anti-globalisation marches have marred past G8 meetings.
Last year, Japanese officials said this summit would be about climate change and reaching agreement on a post-Kyoto Accord framework to cut greenhouse gas emissions, says the BBC's Chris Hogg in Tokyo.
Mr Fukuda had said he would like to get agreement on 50% overall reductions in greenhouse gases by 2050.
But the rising food and oil prices and their effect on the global economy and the world's poorest nations have moved up the agenda.
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