Heads of state and government from the United States, Britain, France, Germany, Italy, Canada and host Japan are meeting in Ise-Shima, a mountainous region about 300 kilometres (200 miles) southwest of Tokyo.
The group, including US President Barack Obama -- who is making a historic trip to the atomic-bombed city of Hiroshima on Friday -- visited Ise Jingu, a shrine complex that sits at the spiritual heart of Japan's native Shintoism.
Obama was the last to arrive at the leafy site under heavy security, a phalanx of black SUVs with tinted windows pulling up alongside a group of schoolchildren waving Japanese flags.
He then walked with Japanese Prime Minister Shinzo Abe along a curved wooden bridge as they approached the forested sanctuary.
In line with tradition, the site's buildings are regularly replaced, but the sprawling shrine is believed to have occupied the same spot for more than 2,000 years.
Abe's decision to take his counterparts to the site -- also a hotspot for domestic tourists -- has raised eyebrows among some critics, however, due to lingering nationalist overtones left over from when Shinto was the state religion.
The group will also get a brief crash course on Japan's world-leading green car technology later Thursday, with a series of bilateral meetings also scheduled.
Among them, Germany's Angela Merkel meets with Canadian Prime Minister Justin Trudeau, who is also holding talks with French leader Francois Hollande.
The sputtering global economy is expected to take centre stage when the formal talks get under way later Thursday, although divisions are likely to remain over whether the world should spend or save its way out of the malaise, with Japan and Germany at odds on the issue.