Four people have been confirmed dead and four others missing as the storm system continued moving northeast at a speed of 55 kilometers (34 miles) per hour after slamming onto the smaller island of Shikoku from the Pacific late Friday.
The eye of the typhoon, with the maximum velocity of its winds down to 90 kilometers (56 miles) per hour, was located near the city of Yamagata, 300 kilometers (188 miles) northwest of Tokyo, at 6:00 pm (0900 GMT), the Meteorological Agency said.
Etau was projected to dwindle into a tropical depression and veer out to the Pacific off the northernmost island of Hokkaido early Sunday, the agency said.
The National Police Agency (NPA) said 15 houses had been damaged and 815 others flooded. Torrential rains triggered 113 landslides and collapsed roads at 18 points.
An official at the NPA security division said that a 45 year-old truck driver was blown off a highway bridge by strong winds into the sea and drowned Saturday in Osaka. He was trying to adjust his cargo.
Elsewhere, a 63 year-old farmer drowned Friday after falling into a swollen river near his rice paddy in Okayama in the west of Honshu.
A woman in Mie, a prefecture on the Pacific side of Honshu, died after strong winds blew her off a terrace into a garden at her home. The 77 year-old hit her head against a concrete block.
And the body of a 71 year-old man was found Friday in a swollen river in Kochi on Shikoku. He apparently slipped into the river from the steps to his boat.
On Shikoku, two construction workers were swept away while clearing a drainage channel and a 17 year-old boy was washed away from a pier by a huge wave Friday, the police official said.
In Nagano, central Japan, a 54 year-old angler was lost in raging water on Saturday.
Thousands of weekend travellers have been stranded at airports and train stations.
Airline officials said 464 domestic flights were cancelled on Friday, stranding some 58,000 people. On Saturday, 180 more flights were cancelled.
Superexpress train runs were cancelled or operated at reduced speeds, causing delays of up to 30 minutes.
Some 18,000 houses were hit by power failures in western Japan, according to electric power companies.