One dead as 'unprecedented' Typhoon Hagibis slams into Japan

Powerful Typhoon Hagibis slammed into Japan on Saturday, killing one even before making landfall and prompting authorities to issue their highest level of disaster warning over "unprecedented" downpours.

More than 7.3 million people were placed under non-compulsory evacuation orders as officials reported serious flooding and several landslides that left at least three people missing. More than 30 were injured, four seriously.

Even before making landfall, Hagibis caused enormous disruption, forcing the cancellation of two Rugby World Cup matches, delaying the Japanese Grand Prix and grounding all flights in the Tokyo region.

It crashed into Japan's main Honshu island just before 7:00pm local time (1000GMT), barrelling into Izu, a peninsula southwest of Tokyo, the Japan Meteorological Agency (JMA) said.

The storm has weakened, but was still packing gusts of wind up to 216 kilometres per hour around an hour before the central eye hit the shore.

And it claimed its first victim hours before arriving on the coast, when strong winds from its outer bands flipped a car in Chiba east of Tokyo and killed the driver.

But it was Hagibis' torrential rain that prompted the JMA to issue their highest-level emergency warning for parts of Tokyo and the surrounding areas, warning of disaster.

"Unprecedented heavy rain has been seen in cities, towns and villages for which the emergency warning was issued," JMA forecaster Yasushi Kajiwara told reporters.

"The possibility is extremely high that disasters such as landslides and floods have already occurred. It is important to take action that can help save your lives."