The Tokyo Olympics had originally been scheduled for 2020 but were postponed by a year because of the pandemic.
Koike, speaking at the Foreign Correspondents' Club of Japan, said organisers were still hopeful venues could be filled with spectators when the Olympics begin in July.
Two days after being named in Australia's Olympic tennis team, Nick Kyrgios said he is "tossing up options" and may opt out of the Tokyo Games due to COVID-19 restrictions.
"Relevant countries should abandon the obsolete Cold War mentality and narrow-minded geopolitical rivalry concept and view correctly and respect people's aspiration in the region and do more things conducive to regional solidarity and cooperation," Chinese foreign ministry spokesman Zhao Lijian said.
Towns and cities lined up to host Olympic training or events have increasingly expressed resistance
Japan's Naomi Osaka said on Sunday that while she has spent her entire life waiting to compete at the Olympics, the risks of holding the Tokyo Games amid the raging COVID-19 pandemic should continue to be carefully discussed.
The schedule announcement comes amid fears that the coronavirus outbreak, labelled a pandemic by the WHO on Wednesday, could have a major impact on the Games.
Ahead of the Quad summit on Friday, China said exchanges and cooperation between countries should contribute to mutual understanding rather than "targeting" a third party and refrain from "pursuing exclusive blocs".
Prime Minister Narendra Modi on Tuesday gifted a Gond art painting, a specimen of Sanjhi art form and a wooden hand-carved box to his fellow Quad leaders from Australia, the US and Japan, sources said.
Union Sports Minister Kiren Rijiju had also said that Olympic-bound athletes will be given priority in the vaccination.
'This also weighed on us, it weighed on me. But in order to arrive at this day today we had to give confidence, had to show a way out of this crisis'.
Japanese Prime Minister Yoshihide Suga reiterated on Thursday his intention to hold the Games.
Japanese Prime Minister Yoshihide Suga said on Thursday the Olympic torch relay scheduled in the city of Osaka has been cancelled amid a resurgence in COVID-19 cases.
According to the tentative plan, September 23-24 is being worked as the expected dates for Modi's US visit.
As an admirer of Japan for close to half a century, I care for Japan and expect Suga to respect the sentiment of his people and cancel the Olympics without further delay, says Rajaram Panda.
US Vice President Kamala Harris would host a separate meeting with the prime ministers of three Quad countries -- India, Australia and Japan -- at the White House to discuss with them the important factors for democracies to go forward, officials said.
On Thursday, the prime minister is scheduled to hold one-on-one meetings with top five American CEOs. Two of them are Indian Americans -- Shantanu Narayen from Adobe and Vivek Lall from General Atomics. The three others are Cristiano E Amon from Qualcomm, Mark Widmar from First Solar, and Stephen A Schwarzman from Blackstone.
In a statement just before leaving for the US, Modi said he will conclude his visit with an address at the United Nations General Assembly focusing on the pressing global challenges including the COVID-19 pandemic, the need to combat terrorism, climate change and other important issues.
Here's what you need to know about the Tokyo Games
Prime Minister Narendra Modi on Thursday is scheduled to have as many as eight meetings, including with Vice President Kamala Harris, on the first working day of his current US trip.
'Risk for the other residents of Olympic village and risk for the Japanese people is zero'
Pak's role in Kabul is not sending a good message to India, a top American lawmaker has said
Quad leaders are also planning to roll out vaccine deliverables and announce a series of measures in the field of healthcare and infrastructure sector, officials in Washington, DC said.
A jump in infections has stoked alarm amid a shortage of medical staff and hospital beds in some areas of Tokyo
Japanese judoka Uta Abe triumphed in the women's 52kg category in Tokyo on Sunday, hours before her brother Hifumi took gold in the men's 66kg final, making history as the first siblings to win gold medals on the same day.
Tokyo 2020 Olympics chief Yoshiro Mori attended a meeting on March 10 that included the deputy head of the Japanese Olympic Committee (JOC) who tested positive for the new coronavirus this week, officials said. Mori, 82, has not been tested because he has no symptoms of the virus and does not meet testing requirements, an official from Mori's office said. Chief Cabinet Secretary Yoshihide Suga told reporters Prime Minister Shinzo Abe met Mori on March 16, without providing details.
Japan has been less severely hit by the coronavirus pandemic than many other advanced economies, but a recent surge in cases spurred it to close its borders to non-resident foreigners and declare a state of emergency in Tokyo and major cities.
Japan has largely avoided the kind of explosive coronavirus outbreaks that have devastated other countries
The Mainichi newspaper earlier reported that the government was planning to ban overseas spectators due to worries they would spread the coronavirus, citing multiple unnamed sources.
Japan's Asahi Shimbun, an official partner of the Tokyo 2020 Olympics, called for the Summer Games to be cancelled in an editorial
The International Olympic Committee and the Japanese government agreed last month to postpone the Games because of the global coronavirus outbreak. The costs of rearranging the Games and who will pay them have yet to be clarified by either the IOC or the Japanese government.
China said on Monday that no 'exclusive cliques' should be formed as it accused some countries of trying to 'drive a wedge' among regional nations citing the 'China threat' and asserted that they will 'end up nowhere'.
Tokyo's state of emergency, the capital's fourth, lasts until Aug. 22, shortly before the Paralympics begin.
"President Biden has had warm and productive early conversations with his counterparts in Australia, India, and Japan, and looks forward to engaging even more directly with our partners in the Indo-Pacific as soon as possible," a senior administration official told PTI.
Organisers have already banned overseas spectators and set a cap on domestic spectators at 50 per cent of capacity
Another downgrade for Tokyo Olympics that have their pomp and public spectacle overshadowed by COVID-19
He also thanked Abe for his leadership in bringing the Olympic Games back to Japan after the Tokyo 1964 Games. His engagement was crucial, IOC President Thomas Bach said.
She added that Suga had encouraged her to make the Games successful but declined to say anything further until after a Tokyo 2020 executive board meeting later in the day, when an official announcement on the post was likely to be made.
The president of the Tokyo 2020 Olympics organising committee, Yoshiro Mori, will resign over a sexist remark that sparked an outcry, two sources said on Thursday, while the former prime minister said he could not let the controversy drag on.
hashtag 'Mori, please resign' was trending on Twitter in Japan