The move comes only four days after Tokyo was placed on alert while the vaccination campaign has covered less than 1% of the population.
The government is expected to official approve the alert status for Kanagawa, Saitama and Chiba and Aichi prefectures in central Japan at a meeting later Friday. It will allow heads of the prefectures to mandate shorter hours for bars and restaurants, along with punishments for violators and compensation for those who comply.
The measures are to begin Monday and continue through May 11.
Many of the cases have been linked to nightlife and dining spots, but they have recently spread to offices, elderly care facilities and schools.
Japan added some 4,300 cases on Wednesday for a total of about half a million with 9,500 deaths.
Suga’s government has been criticized for being too slow in enacting anti-virus measures out of reluctance to further damage the economy.
The surge has also prompted concern among many Japanese about hosting the Tokyo Olympics July 23-Aug. 8. On Thursday, two top officials said there was a possibility the Games could be canceled or even if they proceed, it might be without fans.
The new alert comes with binding orders but only for businesses to close early while measures for residents are only requests, leading some experts to doubt their effectiveness.
Osaka recently declared a medical emergency after its hospitals became overwhelmed with new cases and has moved next week’s Olympic torch relay there off public roads.