Later that same day, upon attaining tropical storm strength, it was named Nanmadol by the Japan Meteorological Agency (JMA).

Nanmadol peaked with winds of 195 km/h (120 mph) and a central pressure of 910 mbar (26.87 inHg) on September 17, and also briefly entered the Philippine Area of Responsibility, where it received the name Josie.

Following peak intensity, the storm began an eyewall replacement cycle and tracked north towards Japan, where it made landfall on Southern Kyushu on September 18.

Later, Nanmadol became a severe tropical storm on September 19, before transitioning into an extratropical low early the next day.

In preparation for the storm, more than half a million people were evacuated in Japan, a rare "special warning" was issued for Kagoshima by the JMA.

[8] At 02:00 UTC on September 12, the United States Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert to the disturbance.

[15] Microwave imaging revealed a well-defined banding feeder from the north and south on the storm's quadrants.

[16] Early the next day, the JTWC upgraded Nanmadol to a Category 1-equivalent typhoon, approximately 578 nautical miles (1,070 km; 665 mi) east-southeast of Kadena Air Base.

[21] Then, it rapidly strengthened into a Category 4-equivalent typhoon as it maintained a 15 nautical miles (28 km; 17 mi) sharply-outlined eye around the eyewall.

[24] Nanmadol entered the Philippine Area of Responsibility, and was named Josie before eventually exiting 5 hours later.

[25] Multispectral animated satellite imagery revealed a 21 nautical miles (39 km; 24 mi) surrounded eye around a deep convection.

[29] Nanmadol weakened further into a Category 2-equivalent typhoon as its structural strength began to rapidly deteriorate.

Japan Airlines and All Nippon Airways cancelled 700 flights,[40] and train services experienced severe delays.

Prime Minister Fumio Kishida mobilized police, firefighters, self-defense forces and another authorities in affected regions.

[45] Several rivers in four prefectures, Kagoshima, Oita, Miyazaki and Kumamoto, went above flood risk levels.

Two people were injured, fallen trees were reported, and some locations in the southeast of the country were left without electricity.

[2] Schools in Busan and Ulsan transitioned to distance learning due to safety concerns.