Weather officials have issued an emergency warning for heavy rain in Saga, Fukuoka and Nagasaki prefectures in western Japan.
Torrential downpours triggered by a weather front have hit northern Kyushu.
Parts of Saga prefecture got more than 100 millimeters of hourly rainfall.
There are already reports of mudslides in Saga Prefecture. Evacuation orders and advisories have been issued for some areas in the three prefectures.
The emergency warning is the highest alert level in the disaster warning scale of one to five.
The Meteorological Agency is advising residents to immediately head to an evacuation center. If it's dangerous to do so, it's instructing people to move to a safer location inside the building they're in now.