Weather officials are warning of strong winds and high waves even after Typhoon Kong-rey, now classified as a severe tropical storm, changes to a low pressure system.
Japan's Meteorological Agency says the tropical storm is likely to become a low pressure system before sunrise on Sunday, as it takes on cold air while heading northward.
But it warns that the system can retain winds as strong as, or stronger than, those of a typhoon.
The agency also says the low can have a more extensive zone of high winds compared to a typhoon in which the storm zone is more concentrated near its center.
A typhoon in September 2004 changed to a low pressure system west of Hokkaido, northern Japan. Then it developed again, logging gusts up to 185 kilometers an hour in northern part of the region.