the city ofso,north of the capital,Tokyo,was hit by a wall of water after the Kinugawa River burst its banks. Helicopter rescue teams have been plucking people from rooftops.
One person has been reported missing in the region and at least 12 are injured.
The rains come a day after Typhoon Etau brought winds of up to 1w5km/h(78mph) to central Aichi prefecture.
This is a scale of downpour that we have not experienced before. Grave danger could be imminent, the chief forecaster at the Jaoan Meteorological Agency(JMA),Takuya Deshimaru ,told an emergency press conference earlier on Thursday
The hardest-hit areas have been lbaraki and Tochigi prefectures. Japan's Meteorological Agency had put both regions on its highest level of slert.