TOKYO: Japanese stocks fell on Thursday as concerns about a spike in domestic coronavirus infections and a potential return of restrictions on economic activity prompted investors to lock in profit on recent gains.

The Nikkei 225 Index was down 0.38% at 29,618.93, as of 0203 GMT, while the broader Topix declined 0.85% to 1,950.57.

The governor of Tokyo is considering adopting emergency measures in response to a sudden increase in coronavirus infections and the spread of a new variant of the virus, according to domestic media.

The western city of Osaka is also set to declare a medical emergency after its number of new infections rose to a record high, which has sparked alarm among public health officials.

Reduced operating hours for restaurants and shops intended to slow the infection rate could hamper economic growth.

In addition, more analysts are starting to express concern about Japan's slow pace of vaccination against the coronavirus.

"Japanese equities may slow down relative to other markets," Masayuki Kichikawa, chief macro strategist at Sumitomo Mitsui Asset Management Co said.

"Markets are placing a lot of emphasis on the size of fiscal stimulus and the vaccination rate. More restrictions would be a negative factor because that would delay a recovery in services consumption."

The underperformers among the Topix 30 were Takeda Pharmaceutical Co Ltd down 2.85%, followed by Mitsubishi UFJ Financial Group Inc losing 2.41%.

In the positive territory, Hitachi Metals Ltd rose 4.36% after the Nikkei newspaper reported that a group led by Bain Capital has emerged as the preferential bidder for a 53% stake in the company worth around $7.3 billion.

Shares in parent company Hitachi Ltd fell 1.03%.

Toshiba Corp rose 1.21% a day after receiving a $20 billion offer from CVC Capital Partners to take it private. In the previous session, Toshiba's shares surged by their daily limit to the highest in more than four years.