Tokyo 2020 president Seiko Hashimoto is “100%” certain the Olympics will go ahead, but warned the Games “must be prepared” to proceed without spectators in the event of a coronavirus outbreak.
There are 50 days until the delayed Tokyo Games begin on 23 July.
Japan is battling a surge in coronavirus cases, with large parts of the country under a state of emergency.
Hashimoto told BBC Sport: “I believe that the possibility of these Games going on is 100% that we will do this.”
Speaking to BBC Sport’s Laura Scott, she added: “The question right now is how are we going to have an even more safe and secure Games.
“The Japanese people are feeling very insecure and at the same time probably feel some frustration at us talking about the Olympics and I think that is giving rise to more voices opposing having the Games in Tokyo.
“The biggest challenge will be how we can control and manage the flow of people. If an outbreak should happen during the Games times that amounts to a crisis or an emergency situation then I believe we must be prepared to have these Games without any spectators.
“We are trying to create as complete a bubble situation as possible so we can create a safe and secure space for people who come in from overseas as well as people who are in Japan, the residents and citizens of Japan.”
A new wave of infections began in April in Japan, where some areas face restrictions until 20 June.
The country began vaccinating its population in February – later than most other developed nations – and so far only about 3% of people have been fully vaccinated.
Hashimoto said it was a “very painful decision” to have no overseas spectators present, but one necessary to ensure “a safe and secure Games”.
“[For many] athletes it’s a once-in-a-lifetime opportunity that they can compete in the Games. To not be able to have family members and friends who have supported them all along must be a very painful thing and that has caused me pain too,” she said.
On the possibility of some countries being prevented from travelling, Hashimoto added: “Who can come to Japan is something the Japanese government will decide.
“If it should happen that a country cannot come to Japan because they do not meet the minimum requirements that the government set, I think that is something we have to listen to what the IOC and IPC feel about that.” – BBC