At least 155 people have died in floods and landslides triggered by torrential rain in western Japan, says the government.
It is the highest death toll caused by rainfall that Japan has seen in more than three decades.
Rescuers are now digging through mud and rubble in a race to find survivors, as dozens are still missing.
About two million people have been evacuated from the region after rivers burst their banks.
Authorities have opened up school halls and gymnasiums to those who have been displaced by the rainfall.
There remains a risk of landslides, with rain-sodden hilltops liable to collapse.
"I have asked my family to prepare for the worst," 38-year-old Kosuke Kiyohara, who has not heard from his sister and her two sons, told AFP.
Prime Minister Shinzo Abe has cancelled an overseas trip to deal with the flood crisis.
More than 70,000 rescue workers, including the fire service and the army, are involved in the relief effort.
Flood warnings are still in effect for some of the worst hit areas, including the Okayama prefecture in the southern part of Japan.
But more settled weather is expected over the next few days which is likely to help with rescue efforts.
"We are checking every single house to see if there are people still trapped inside them. We know it's a race against time, we are trying as hard as we can," an official with the prefecture's government told AFP.