The Tokyo metropolitan government has started calling on commuters to avoid using trains during the morning rush hour to ease congestion.
Tokyo officials launched the campaign on Monday as part of the run-up to the next year's Olympics and Paralympics to be held in the city.
About 980 companies and organizations are taking part.
For instance, the operator of the Tozai subway line runs two extra trains on business days during the early morning hours.
Before the start of the rush hour on Monday, company workers and others were getting on and off one of the trains at a station in Koto Ward.
A man in his 40s said he had started using trains before 7 AM to avoid the stress of travelling on packed trains. He said he initially had trouble getting up early, but has gotten used to it.
An official with the subway company said chronic congestion causes trouble for passengers. He said the company will call on commuters to refrain from using trains during rush hours.
Tokyo officials say participating railways will tell passengers when their trains are crowded, and employers will call on workers to shift their commuting schedules.
The campaign will last until February 1st.
The metropolitan government first held such a campaign in the summer of 2017. This is the first time it has been held in winter.