Japan's Health Ministry officials have confirmed the number of patients with serious conditions has topped 1,000 -- the highest since the start of the pandemic.
Despite a state of emergency in place for Tokyo and 10 other prefectures, rates continue to escalate.
The total number of people who have tested positive stands at more than 340,000 nationwide.
Authorities say medical capacities are strained in many parts of the country.
It's been 11 days since Tokyo, the biggest hotspot, was put under the emergency declaration. Yet Tuesday saw 1,240 new cases confirmed in the capital.
The daily tally topped 1,000 for the seventh straight day.
Local governments are taking their own actions in responding to the pandemic. Hiroshima Prefecture in western Japan decided to conduct large-scale PCR tests targeting 800,000 citizens as early as next month.
But officials say the fight against the virus needs to be stepped up, as new evidence shows that a more contagious strain could be spreading within Japan.
Three adults in central Japan's Shizuoka Prefecture were confirmed on Monday to be infected with the new variant first found in the UK. It's the first time that people with no clear transmission route have been diagnosed with the variant.
The World Health Organization says the new variant can spread more quickly. An infectious disease expert says it changes the outlook on the pandemic.
Professor Hamada Atsuo of Tokyo Medical University said, "It's becoming very hard for us to imagine how the current third wave will turn out. But I think the period of the pandemic might linger."
Hamada says people must prioritize basic preventive measures, like wearing masks and washing hands.