The death toll from Typhoon Hagibis has risen to 40.
Some 16 people also remain missing as Japan deals with the destructive storm.
More than 110,000 police officers, firefighters, soldiers and coastguard personnel – as well as 100 helicopters – have been mobilised for Monday's rescue operations.
Rescue crews were digging through mudslides and searching near rivers in central and northern Japan.
Authorities have warned more mudslides are possible, with heavy rain forecast in central and eastern areas of the country on Monday.
Prime minister Shinzo Abe said: "There still are many residents who have yet to be accounted for. Our people in uniform are working day and night in search and rescue operations.
"Damage has been made in an extremely wide range of areas, and more than 30,000 people are still being forced to remain in the state of evacuation.
“It is our urgent task to offer meticulous support to those who have been affected."
Chief cabinet secretary Yoshihide Suga said: "Rain is expected in affected areas today. Because of the rain we have seen so far, levels of water are high in some rivers and soil is loose in some areas.
"Please remain on your guard for landslides and river overflows."
Hagibis unleashed torrents of rain and strong winds on Saturday that left thousands of homes on the country’s main island flooded, damaged or without power.
Hagibis dropped record amounts of rain in some spots, causing Japan's many rivers to overflow.
Additional reporting by agencies.
