Japan sent tens of thousands of troops and rescue workers to save stranded residents and fight floods caused by one of the worst typhoons to hit the country in recent history.
At least 30 people were killed in the typhoon that left vast sections of towns under water, public broadcaster NHK said.
Another 15 were missing and 177 injured by Typhoon Hagibis, which paralysed Tokyo yesterday and dumped record levels of rain around Japan.
About 100,000 homes were left without power.
Ten rivers in central and northeastern Japan burst their banks while dozens of others had overflowed, the government said, complicating rescue efforts.
Evacuation centres filled up with residents, while some perished on their way to seek shelter, washed away by the flooding.
Some of the worst damage hit Nagano city, central Japan, where the Chikuma River burst its banks, inundating large swaths of land in brown water and forcing military helicopters to airlift stranded people from homes.
Hagibis, which means "speed" in the Philippine language Tagalog, made landfall on Japan's main island of Honshu yesterday and headed out to sea early today.
Prime Minister Shinzo Abe convened an emergency meeting of relevant ministers and sent the minister in charge of disaster management to affected areas.
"The government will do everything in its power to cooperate with relevant agencies and operators working to restore services as soon as possible," he said. The government set up a task force to deal with the damage.
NHK said the full extent of the widespread damage was only beginning to emerge because many areas remained under water.
Some 425,000 homes were without power, the government said, reviving fears of a repeat of the weeks-long power outages suffered after another typhoon hit east of Tokyo last month.
In Fukushima, north of the capital, Tokyo Electric Power Co reported irregular readings from sensors monitoring water in its Fukushima Daiichi nuclear plant overnight. The plant was crippled by a 2011 earthquake and tsunami.
Landing restrictions at Tokyo's Narita and Haneda airports were lifted but more than 800 flights were cancelled for the day, NHK said, as were some Shinkansen bullet train services to the worst-hit areas.
Just last month, another strong storm, Typhoon Faxai, destroyed or damaged 30,000 houses in Chiba, east of Tokyo, and caused extensive power outages.
The Rugby World Cup match between Namibia and Canada in Kamaishi today was cancelled, although the Japan-Scotland match went ahead. Two matches were cancelled yesterday.