Authorities warned that the Koza River may already be overflowing, and evacuation orders were issued for residents in Kozagawa and Kushimoto.
On Wednesday at 4:30 a.m., Tropical Storm Jangmi made landfall on southern Wakayama Prefecture, prompting the Japan Meteorological Agency to issue a Level 5 emergency flood warning for the Koza River.
This marks the first time authorities have issued a Level 5 emergency flood warning since the Japan Meteorological Agency and the land ministry recently revised their weather warning system.
Linear rainbands formed in southern Wakayama and Tokushima Prefecture early Wednesday, triggering emergency evacuation warnings for residents in Kozagawa, Kushimoto, and the city of Anan to protect their lives.
Authorities issued Level 4 urgent warnings for heavy rain, landslides, or river flooding across Shizuoka, Mie, Nara, and Wakayama, ordering residents in many areas to evacuate immediately.
The Japan Meteorological Agency forecasts up to 200mm of rainfall in the Tokai and Kanto-Koshin regions, with up to 120mm in the Tohoku region over a 24-hour period until 6 a.m. June 4.