Heavy rain from typhoon Megi lashed South Korea and Japan on Thursday, prompting the evacuation of some 3,000 people and leaving at least 12 dead. Some 165 Japanese children were trapped at a nature centre.
Three people were killed in South Korea and two reported missing, while the death toll in Japan rose to nine after flooding and landslides due to the typhoon.
Megi, which means "catfish" in Korean, was pushing north at a speed of 55 km (34 miles) an hour and threatening to make landfall in northern Japan on Friday, forecasters said. It was 170 km (106 miles) north-west of western Shimane prefecture at 0500 GMT.Many of those killed in both nations were elderly.
In Japan, they included a couple on Shikoku island who died when their house was engulfed by a landslide.
Others were swept out to sea or drowned in irrigation ditches, officials said. A 75-year-old woman in South Korea died when she slipped while trying to cross a stream.
Japan's latest confirmed fatality was a 45-year-old woman swept away while trying to leave her home.
Japanese television footage showed muddy waters swirling around a traditional home and roads made impassable by landslides. Railroad tracks dangled in mid air after supporting banks were washed away.
More than 2,700 in South Korea and around 400 in Japan were evacuated from their homes.
About 165 Japanese primary school students spent an anxious night trapped without water or electricity at a nature centre after being cut off by heavy rains that triggered a landslide.
Several children were evacuated by helicopter, including one girl who was showing symptoms of appendicitis, public broadcaster NHK television said.
South Korea's Yonhap news agency reported military personnel there had been ordered to use explosives to blow a channel for flood water that threatened to swamp a village near the south-western city of Kwangju.
Some 205 mm (8 inches) of rain had fallen on some areas of the Japanese island of Shikoku by 9 am (0000 GMT) on Thursday and forecasters said another 200-250 mm (8-10 inches) was expected in the next 24 hours.
Winds were gusting up to 126 km (78 miles) per hour.
The South Korean port of Pusan, which is located some 400 km (250 miles) south-east of Seoul and is the world's fifth-busiest, suffered little damage as shipping firms had taken precautions ahead of the typhoon's arrival, a port official said.