The biggest headache is the resurgent coronavirus, with countries like India and Brazil battling new variants and a fresh rise in cases. In Japan, vaccinations have been the slowest among developed economies, as Tokyo has lurched in and out of soft lockdowns. Infections are on the rise, and experts worry the city is on the cusp of an "explosive "jump in cases.

As a result, foreign spectators have been barred, parts of the torch relay have been re-routed, and the organizers are yet to decide what to do with the domestic audience. This has caused major challenges for sports venues and travel agencies, already grappling with restrictions to block the virus.

"The situation is constantly shifting. Even in the last few months the coronavirus situation has changed massively, and it will continue to do so, and it's very challenging to continue preparations when we don't know what the situation will be in the future," said Hidemasa Nakamura, the top organizing committee official overseeing logistical preparations for the Games.