At least three people have been killed in the seaside town of Atami after torrential rains at the weekend touched off a succession of landslides to send torrents of mud and rock ripping through streets in one part of the city. In some places, more than a usual July's worth of rain fell in just 24 hours.
The torrential rain and landslides are a reminder of the natural disasters - including earthquakes, volcanic eruptions and tsunami - that haunt Japan, where the capital Tokyo is to host the summer Olympics beginning this month.
"We want to rescue as many victims ... buried in the rubble as soon as possible," Prime Minister Yoshihide Suga told reporters, adding that police, firefighters and members of the military were giving their all to do so.
The third person was confirmed dead in the seaside city of Atami 90 km (60 miles) southwest of Tokyo, where 113 are believed missing, spokesperson Hiroki Onuma told Reuters.
That fatality was a woman, Kyodo news agency said.
"We're in touch with various groups and pushing forward with the searches," Onuma said.
Over the weekend some 20 people were said to be unaccounted for, but the number rose sharply on Monday as officials began working from residential registers rather than phone calls from people unable to reach family members, he said.
Around 130 buildings were affected on Saturday morning when landslides ripped through Atami, a hot springs resort town set on a steep slope that leads down to a bay.
The water, mud and debris are thought to have flowed along a river for about 2 km (1.2 miles) to the sea, local media said.
"My mother is still missing," one man told NHK public television. "I never imagined something like this could happen."
Though Onuma said rain had stopped in Atami for now, more is forecast, raising the possibility of further landslides.
"The situation is unpredictable," he said.