The Tokyo Metropolitan Government reported 131 COVID-19 cases on Saturday, marking three consecutive days above 100 and the highest tally since May 2.
Saturday's count prompted Gov. Yuriko Koike to urge residents not to travel beyond Tokyo's borders.
"I want Tokyo citizens to refrain from making any nonessential trips to other prefectures," Koike told reporters.
Infections are growing among younger people, and many of them are being traced to host and hostess bars and other nightlife destinations.
Koike said such infections are raising the overall count, with infections among people in their 20s and 30s making up around 100 of the 131 cases.
Tokyo reported 107 cases on Thursday and 124 on Friday. Saturday's figure is the capital's highest single-day count since 154 on May 2. The peak was 206 on April 17.
The worsening trend has stoked fears of a resurgence of the virus in the capital and in the surrounding prefectures in the Kanto region.
While urging the public to exercise caution, Koike has stressed that the metropolitan government will make efforts to reopen the virus-hit economy. The central government has said it does not see the need to immediately revive the state of emergency despite the climbing infections.
Saturday's cases brought Tokyo's total infection count to date to 6,654.
Your news needs your support
Since the early stages of the COVID-19 crisis, The Japan Times has been providing free access to crucial news on the impact of the novel coronavirus as well as practical information about how to cope with the pandemic. Please consider subscribing today so we can continue offering you up-to-date, in-depth news about Japan.