It was not necessary to reintroduce a state of emergency despite the record rise, the country’s top government spokesperson said on Thursday.
Chief cabinet secretary Yoshihide Suga said about 80 per cent of the new cases were among people in their 30s or younger.
He added that it was not possible to reduce infection risks to zero after the country lifted a state of emergency in May.
Positive cases of Covid-19 in Tokyo have increased in recent weeks as health authorities increased targeted testing among workers in the city’s night-life districts.
The record one-day total of 224 surpassed the previous high of 206 on 17 April, when the capital and other major cities were under a state of emergency.
Tokyo’s governor, Yuriko Koike, has attributed the recent spike partly to an increase in testing.
Ms Koike, who won re-election as governor on Sunday, has promised to boost testing capacity to 10,000 a day.
“Although the increase in [testing] is a contributing factor, we need more vigilance in monitoring the trend in infected people,” she said in remarks streamed online.
“Infections in the night-life district are still making up a certain number of cases, but we’ve recently also seen an increase in cases among young people dining together.”
As the number of serious cases and deaths remain relatively stable, Japan has shifted from a phase of drastic containment measures to one merging risk control and economic activity.
It is due to relax restrictions on large gatherings on Friday, allowing events to be held with up to 5,000 people, an increase from the current 1,000.
Japan has fared better than most nations in dealing with the pandemic so far.
Japan has had more than 20,000 confirmed coronavirus cases and 980 deaths. Globally, the coronavirus has killed half a million people.
Additional reporting by Reuters