Japan has reached a new stage in novel coronavirus infections, with case numbers seeing a rapid increase in the capital.

Tokyo Gov. Yuriko Koike has asked people to stay indoors this weekend, and the governors of neighboring prefectures are also going along with this move. The country needs to put its full efforts into preventing an explosion of infections.

For two days running, the number of new cases of the virus in Tokyo has topped 40 per day, and the source of infection is unknown for many of them. In other words, clusters of the virus may be breaking out undetected. At the same time, the number of infected people returning from overseas is increasing, heightening the risk of a further spread of infections.

From the outset, Tokyo has been slow to respond to cases of the new coronavirus.

A spike in infections in Tokyo, with its overconcentration of people, would inflict untold damage on society and the economy. In spite of this, the kind of strong messages seen from the leaders of other cities have been scarce. Tokyo's stance finally changed only around the time that postponement of the Summer Olympic Games started looking inevitable.

On the three-day weekend before Koike's request for people to remain at home, many people visited famous cherry blossom-viewing spots in the capital. A call for caution should have been given much earlier.

The Tokyo Metropolitan Government was also passive when it came to releasing information. On its website, it has not revealed the areas of residence of infected people nor the circumstances surrounding their infections. It is important to protect people's privacy, but under such circumstances, people don't know how to react, and they could end up feeling uneasy.

Gov. Koike announced that the capital had "reached a serious phase regarding an explosive rise in the number of infections." A range of measures must be formulated to combat COVID-19.

First of all, infections routes need to be pinpointed so that efforts can be poured into stamping out infection clusters. If the number of patients rises suddenly, then it will become necessary to ask those with light symptoms to recover at home.

On March 26, the central government launched a headquarters to counter the coronavirus based on the country's special measures law, and it became possible for the prime minister to declare a state of emergency. Koike even referred to a possible lockdown. It is essential for prefectures in the Tokyo metropolitan area to collaborate closely with each other.

The Tokyo government plans to resume school classes from the start of the new term in April, with students at schools run by the metro government set to commute at different times. Depending on the spread of infections, officials should probably reconsider the resumption of schools including elementary and junior high schools across different municipalities in the capital.

Even now, young people can still be seen in downtown areas at night. In the meantime, following the request for people to stay indoors, people have started hoarding food products and other items. This is a time when people need to cooperate with the request to stay indoors and calmly respond to the situation.