Tokyo Olympic officials say they have reached a "basic agreement" with all 68 domestic sponsors to extend their contracts into next year to support the postponed Games.
Yoshiro Mori, the president of the organising committee, said at an on-line briefing that the new contributions "will exceed" 22 billion yen, or about $A275 million, to patch up holes in the growing budget.
Japanese domestic sponsors had already contributed a record of $4.3 billion to the local operating budget, and the new money pushes the total past $4.6 billion.
This is at least twice - perhaps three times - as large as any previous Olympics and is driven by Dentsu Inc,, the giant Japanese advertising company that is also the marketing agent for the Tokyo Games.
Toshiro Muto, the chief executive of the organising committee, said Dentsu had conducted the negotiations.
"It's not that we went through negotiations to force the companies to invest," Muto said.
Mori also said the companies were not "pushed".
Mori acknowledged that many companies were facing tough financial times.
It's also clear that the Tokyo Olympics have become a priority for Japan's national government, which would make it difficult for companies not to renew.
"We have also heard from our partners about the difficult situation that each of them is facing in the midst of the pandemic and the unprecedented economic crisis," Mori said.
The Japanese newspaper Nikkei reported earlier this month that each of the 15 so-called "Gold Partners" would contribute about $13 million each.
Some of the Gold Partners include well-known names like Canon, Fujitsu, and the Mizuho Financial Group.
Nikkei is also a domestic sponsor along with other dailies including Asahi, Mainichi, Yomiuri and several smaller newspapers.
Sponsors like the airline ANA and Japan Airlines are among those struggling during the pandemic, but they are also reported to be contributing.
The postponed Olympics are to open on July 23, 2021, followed by the Paralympics on August 24.
Japan has contained COVID-19 better than most countries, and there is skepticism among the public about inviting 15,000 Olympic and Paralympic athletes into the country.
About 3000 deaths attributed to COVID-19 have been reported in Japan, a country of about 125 million.