Tokyo and three neighboring prefectures have confirmed their highest new infection counts of the coronavirus since the second state of emergency was lifted last month.
The capital reported 759 new cases on Saturday. An official says the pace of increase is accelerating.
Residents have been living with stricter anti-coronavirus measures in the face of a recent surge in the number of cases. Officials are eager to cut foot traffic to curb the spread of virus strains that are said to be more transmissible.
The western prefecture of Osaka has recently seen the largest number of daily infections in the country. It reported 1,161 new cases on Saturday, exceeding 1,000 for five days in a row.
Vaccinations for the elderly began in Japan last Monday. Some are getting their shots over the weekend.
Priority vaccinations for health care staff started in February. But progress has been slow.
While about 4.8 million workers are estimated to be eligible, only 14 percent have completed two vaccinations so far.
The health ministry says that by the first half of May, it expects to have provided enough doses to give all eligible people two shots.