Tokyo, hosting the Olympics while under a state of emergency, reported 4,066 new COVID-19 cases on the last day of the games on Sunday, topping 4,000 for the fifth straight day.
Tokyo confirmed 1,359 daily COVID-19 cases on July 23 when the Olympics formally started. Since then, the number of daily infections has entered an upward trend.
The metropolitan government also reported Sunday that Tokyo's seven-day rolling average of COVID-19 cases has increased to 4,037 per day, surpassing 4,000 for the first time and rising 30 percent from the previous week.
Stricter measures against the COVID-19 pandemic were introduced on Sunday in eight prefectures newly placed under a quasi-state of emergency, requiring restaurant operators to cut opening hours and suspend serving alcohol.
Fukushima, Ibaraki, Tochigi, Gunma, Shizuoka, Aichi, Shiga and Kumamoto, the eight prefectures joined Kyoto, Fukuoka, and other three prefectures already subject to such restrictions effective for all the 13 areas until the end of the month.
By Friday, Japan's cumulative total of confirmed COVID-19 cases exceeded 1 million, and on the same day, Japan's health ministry reported Japan's first case of the Lambda variant of the virus, which might be more infectious and more resistant to vaccines, according to Japan's National Institute of Infectious Diseases.