At least 25 people were unaccounted for on Friday after a river burst its banks in Japan's Ibaraki prefecture as a result of torrential rains triggered by typhoon Etau.
The Japan Meteorological Agency (JMA) issued its highest warning for Sendai, the capital of Miyagi prefecture, where more than 400,000 people evacuating the region ahead of unprecedented torrential rains, reported Xinhua news agency.
While in Joso, located 50 km north of Tokyo, hundreds of people were left stranded overnight as the Kinugawa river burst its banks for the first time in 66 years.
Those who live in the vicinity of the inundated areas had to flee to evacuation centres, while others were unable to escape from their flooded homes, rescue officials said.
Heavy rains had caused houses to be swept away, with muddy floodwaters also submerging a number of homes, as police and rescue services attempted to save those who had escaped to rooftops.
The Shibui river in the city of Osaki also burst its banks on Friday, flooding nearby residential areas, according to the latest official reports.
Disaster Management Minister Eriko Yamatani said the government will "extend maximum support" to secure relief supplies and establish emergency shelters.