Japan hit a new daily high in Covid-19 cases yesterday, with at least 1,651 cases nationwide, according to a tally by broadcaster NHK.
Economy Minister Yasutoshi Nishimura, who is in charge of the coronavirus response, warned of more stringent measures if the infections continued to spike, leading to an overburdening of medical institutions.
"We are not at a point where a state of emergency must be declared, but we need to have the strongest sense of caution," he said.
Experts say the current surge is particularly worrying, given that socio-economic activities have, for the most part, returned to pre-Covid-19 days.
Officials have in recent days stressed the infection risks posed by nomikais - after-work drinking parties - that are common at workplaces or among friends.
Adding to these fears is the onset of winter, when people tend to spend more time indoors in heated, poorly ventilated rooms.
In response to the surge, Mr Nishimura said capacity limits for large events will be kept in place for another three months until the end of next February.
Japan has capped attendance of events at 10,000 people or 50 per cent of a venue's capacity, whichever is lower, though in a trial last month, 32,000 baseball fans were packed into a Yokohama stadium over three match days.
The government has also said the Go To Travel domestic tourism campaign should not be made a scapegoat for the rise in infections, despite a surge in asymptomatic cases in popular tourist destinations with large urban populations.
Japan's worst day in its battle against the coronavirus comes despite the nation having entered into agreements to relax travel restrictions with countries that have largely managed to put a lid on infections, including Singapore, China and South Korea.
The Chinese mainland registered 15 new cases on Wednesday, the national health authority said yesterday. This brings China's tally to 86,299. South Korea added 143 cases yesterday, raising its caseload to 27,942. Japan's total is 113,816 cases.
Tokyo recorded 393 cases yesterday, its highest since Aug 8. Infectious disease expert Norio Ohmagari, who is advising Tokyo authorities, warned that this portends the start of a sharp rise in infections.
Osaka logged 231 infections on the third straight day it has had more than 200 cases.
Aichi, where the city of Nagoya is situated, had 143 cases, the highest figure since Aug 8.
New daily peaks were logged in areas like Hokkaido, with the bulk of the 236 cases in Sapporo.
Kanagawa, which is part of the Greater Tokyo region, had 147 cases. And Hyogo, where the city of Kobe is situated, had 81 cases.
These spikes come even as Tokyo prepares to welcome two high-level visitors.
International Olympic Committee chief Thomas Bach will make a four-day visit from Sunday, and Australian Prime Minister Scott Morrison will make a two-day trip from next Tuesday. Mr Morrison will be the first head of state in Tokyo since the coronavirus outbreak.
Mr Bach, who will be on his first visit to Tokyo since the decision was made in March to postpone the Olympic Games by a year, said discussions over the possibility of an outright cancellation of the Games will not be on the table.
A Japanese panel, tasked to look into virus prevention measures, said yesterday that it will decide by spring whether to set audience caps at sporting venues, and whether to even allow foreign spectators into the country. In the event they are allowed, however, they will most likely be exempted from serving a 14-day quarantine.
Japanese Prime Minister Yoshihide Suga has asked his Cabinet to compile a third supplementary budget for the current fiscal year to finance a new economic stimulus package that is likely to include more support for businesses, as well as funding for an extension of the Go To Travel campaign.
Even without the latest spike, the Covid-19 crisis has driven up bankruptcies and suicides across Japan, while also pushing unemployment to a three-year high.
"The government must work at full force to allow social and economic activities as well as measures to slow the spread of the virus to keep going as we prepare for winter," Mr Suga said.