Typhoon Dujuan has left 12 people dead and three missing in Japan, the country's Fire and Disaster Management Agency (FDMA) reported on Sept. 24, after heavy rain triggered landslides, floods and embankment failures across the Kanto region east and south of Tokyo. Seven deaths were recorded in Chiba Prefecture, four in Kanagawa and one in Miyazaki, according to an FDMA summary compiled by The Watchers. The agency described the figures as preliminary.

The storm, known in Japan as Typhoon No. 25, approached the Izu Islands and the Kanto region on Sept. 21, during the country's autumn holiday stretch, then moved northeast over the Pacific. It became an extratropical cyclone far east of Japan at 9 p.m. JST on Sept. 22, according to Japan's transport ministry. The worst damage came from water rather than wind, as prolonged torrential rain fell on steep hillsides and low-lying farmland.

For residents, the danger has not fully passed. Chiba Prefecture warned on Sept. 23 that saturated ground could produce more landslides even with light rain, and urged caution over rising rivers and flooding in low-lying areas.

Landslides in Kamogawa and Miura

Many of the deaths followed landslides that struck homes and roads. In Kamogawa, on Chiba's Boso Peninsula, authorities confirmed on Sept. 23 the death of a man in his 70s who had been missing after a landslide, raising Chiba's toll to seven. In Miura, Kanagawa Prefecture, landslides sent mud into homes, and a collapsed apartment building had to be demolished while a stretch of National Route 134 stayed closed.

Tallies shifted quickly during the search. On the evening of Sept. 23, the reported toll stood at 10 deaths with four people missing, The Nation reported, before the national agency's Sept. 24 table listed 12 deaths nationwide. Differences between prefectural counts and FDMA figures are common in the first days after a disaster and reflect timing and how deaths are classified.

Kanagawa's Sept. 24 assessment listed three destroyed homes, two in Miura and one in Yokosuka, along with six slope failures in Yokohama. In Chiba, flooding reached 884 residential buildings above or below floor level, the prefectural government said on Sept. 24, a total it expected to rise because homes in Narita had not yet been counted, Jiji Press reported.

Record Rain and Historic Breaches at Lake Inbanuma

At Oshima in Tokyo's Izu Islands, the Japan Meteorological Agency recorded 832 millimeters (32.76 inches) of rain in 48 hours, the highest total since that station's records began in December 1991. It topped the previous mark of 824 millimeters (32.44 inches) set in October 2013, according to JMA's historical rankings. JMA had earlier issued its highest-level landslide warning for Oshima, The Watchers reported.

On the mainland, Kanagawa reported 365.5 millimeters (14.39 inches) in Miura and 342 millimeters (13.46 inches) at Yamate in Yokohama through the morning of Sept. 23. In northern Chiba, about 100 meters (328 feet) of the North Inbanuma embankment failed near Narita on Sept. 22, and further breaches followed along a drainage channel and the Nagato River in Sakae, flooding surrounding farmland and neighborhoods. The Japan Water Agency said the water level in the western part of the lake reached a record 5.04 meters. The breaches were the first since the lake's reclamation project was completed in 1969, according to the prefectural government. The national transport ministry sent its emergency technical teams to help restore all three breach sites.

The flooding also hit livelihoods. Most of the roughly 100,000 ornamental carp and goldfish at one Narita fish farm were washed away, with damage estimated at about 1 billion yen, and an Inbanuma fisheries cooperative lost most of its cultured eels, The Japan Times reported.

Record Rain on Steep Ground Explains the Toll

The evidence supports a clear physical chain: record rainfall fell on steep coastal hills and on low-lying land around Lake Inbanuma, where water rose above its previous record. Slopes failed where the ground became saturated, and earthen embankments gave way as lake and river levels climbed.

No formal study has examined whether climate change influenced this particular storm, and none is needed to explain the immediate damage. The FDMA figures remain preliminary, and final damage assessments have not been released.

Lessons for Flood-Prone Communities Beyond Japan

The disaster carries lessons for coastal and river communities worldwide, including in the United States. Earthen embankments and levees that have held for decades can fail when water levels exceed anything in the historical record, and landslide risk can persist for days after the rain stops. Chiba's warning that even light rain could trigger new slides mirrors guidance U.S. agencies issue for burn scars and saturated hillsides.

The greatest burden in Japan has fallen on residents of steep neighborhoods in Miura and Yokosuka, farm and fish-farming communities around Lake Inbanuma, and rural areas of the Boso Peninsula. Travelers with plans in the Tokyo region should check rail and road advisories, as some routes on the Boso and Miura peninsulas remained restricted after the storm.

Search operations for the missing continue in Chiba and Kanagawa, and embankment repairs at Lake Inbanuma are ongoing. The next FDMA reports will show whether the toll changes as searches conclude. For now, the key takeaway is that Dujuan's deadliest effects came from rain and saturated ground, not wind, and that risk can outlast the storm itself.

What Readers Want to Know

How many people died in Typhoon Dujuan?

Japan's Fire and Disaster Management Agency reported 12 deaths and three people missing as of Sept. 24: seven deaths in Chiba, four in Kanagawa and one in Miyazaki. The figures are preliminary.

Where did the worst damage occur?

Chiba and Kanagawa prefectures near Tokyo were hit hardest, with deadly landslides in Kamogawa and Miura and embankment breaches around Lake Inbanuma in northern Chiba.

How much rain fell?

Oshima in Tokyo's Izu Islands recorded 832 millimeters (32.76 inches) in 48 hours, a record for that station. Miura in Kanagawa received about 14.39 inches.

Why was eastern Japan hit so hard?

Record rain fell on steep slopes and on low-lying land around Lake Inbanuma, where water rose to a record level, triggering landslides and overwhelming earthen embankments.

Is the danger over?

Chiba officials warned that saturated slopes could still fail even with light rain, and search operations for the missing were continuing.

Did Typhoon Dujuan affect the United States?

No. The storm moved northeast over the Pacific and became an extratropical cyclone far east of Japan on Sept. 22.