Tropical Storm Danas is moving up the East China Sea, approaching remote islands of Japan's Okinawa Prefecture.
The Japan Meteorological Agency said that at noon on Thursday, the large storm was moving north at 25 kilometers per hour, with a maximum sustained wind speed of 72 kilometers per hour.
The storm is forecast to bring fierce winds and waves up to 7 meters high to coastal areas of Okinawa on Thursday and Friday as it keeps moving north.
The storm is also activating a seasonal rain front hanging over parts of Japan, bringing heavy rain to western and central areas of the country.
During the hour through 2 p.m., Kaiyo Town in Tokushima Prefecture recorded 55.5 millimeters of rain. Early afternoon radar analysis showed an estimated 120 millimeters of rain per hour in and around Sukumo City in Kochi Prefecture.
The approach of the storm and the rain front are expected to create unstable atmospheric conditions in eastern and western Japan through Saturday, bringing localized torrential rain.
The agency is advising residents to stay alert for heightened dangers of landslides, flooding, lightning and tornados.