Organizers of the Tokyo Olympics said on Wednesday athletes and officials should not use public transport without permission, and asked them to wear face masks at "all times" during the event, except when eating or sleeping.
The organizers unveiled a "playbook" detailing COVID-19 measures that will be taken during the Summer Games this year. They also asked fans not to sing or chant to support athletes.
Officials said they must make a decision on the number of overall spectators that would be allowed by Spring.
Japan has been hit less severely by the pandemic than many other advanced economies, with fewer than 6,000 deaths recorded so far. But a recent surge in cases forced it to close its borders to non-resident foreigners and declare a state of emergency in some parts of the country.
There are public fears that an influx of athletes will spread the virus, and polls show a majority of Japanese residents oppose the Games taking place this year.
An official for the Tokyo 2020 Organizing Committee said it was important to ensure that the local medical system and the Olympics were both sustainable.
Pierre Ducrey, the International Olympic Committee's games operations director, told a joint press briefing that the games would be a "different experience."Delegations and staff will be required to appoint a COVID-19 liaison officer, who will be responsible for ensuring the participants follow the guidelines. The playbook also advises against shopping at the airport upon arrivals in Japan.