Tokyo Governor Yuriko Koike has said it may be necessary to a stage a "simplified" Olympics next year and that organisers were already discussing possible changes.
Koike's comments on the impact of the COVID-19 pandemic come after the Yomiuri newspaper reported that various options, such as mandatory coronavirus testing and having fewer spectators, were being considered by organisers.
John Coates, the head of the International Olympic Committee's inspectorate for Tokyo, has said a lack of a defence against the virus threatened the Games and organisers had to start planning for what could be a "very different" Olympics if there were no signs of COVID-19 being eradicated.
Koike did not go into details but said such discussions were necessary.
"Holding the Olympic and Paralympic Games calls for sympathy and understanding of Tokyoites and the Japanese people," he said.
"For that, we need to rationalise what needs to be rationalised and simplify what needs to be simplified."
The Yomiuri, citing government and organising committee sources, said making Polymerase chain reaction (PCR) tests mandatory for all spectators - in addition to athletes and staff - and limiting movement in and out of the athletes' village were among the options Japan would discuss with the IOC.
The IOC and Japanese government in March took the unprecedented decision to delay the Games, which had been due to start in July, for a year due to the coronavirus outbreak.
A further delay beyond 2021 has been ruled out.
The new coronavirus has infected more than 6.4 million people and killed about 380,000. Japan has around 17,000 infections and 900 known deaths to date.