|The typhoon has been preceded by heavy rains which flooded a large part of central Japan [Al Jazeera English]
A powerful typhoon has smashed into disaster-ravaged Japan after rains that preceded it killed at least four people.
Two people remained missing in the central prefecture of Gifu, including a young boy who disappeared on his way home from primary school.
"Roke typhoon landed at around 2pm [0500 GMT]," on Wednesday near Hamamatsu in Shizuoka prefecture, a meteorological agency official said.
The Japanese government warned all those in the path of the typhoon to heed any evacuation orders immediately.
"We need to be extra vigilant against a potential disaster caused by heavy rains, strong winds and rough seas along a wide area from western to northern Japan," Osamu Fujimura, chief cabinet secretary, said at the regular morning news conference in Tokyo.
The typhoon comes six months after a devastating earthquake and tsunami killed thousands and sparked a crisis at the Fukushima nuclear plant, where workers were reinforcing the facility against the storm.
The typhoon had been preceded by heavy rains on Tuesday which flooded a large part of central Japan.
Over a million residents around the city of Nagoya had been advised to evacuate overnight as parts of the city were flooded by advance rains. In some parts rescue workers had to take residents to safer ground in boats after rising waters cut off whole residential areas.
"Many people were caught unaware during the Great Eastern Disaster and I didn't want that to happen again, so I decided to get here as early as possible," one resident of Nagoya said after taking refuge in one of the many local evacuation centers across town.
Another resident said: "The water levels got to right under the bridge. I was totally taken aback that when I saw it, I ran home. That's when I saw there was an evacuation advisory."
A number of expressways have been closed, while more than 200 flights are to be cancelled for Wednesday, according to NHK news agency.
Car giant Toyota said it was temporarily shutting 11 of its 15 Japanese plants, which lie in the path of the storm.
The storm was expected to travel northeast, possibly towards the crippled Fukushima nuclear plant, where workers are still battling to control persistent radiation leaks.
"We have taken every possible measure against the typhoon" at Fukushima Daiichi, said Naoki Tsunoda, a spokesman for Tokyo Electric Power Co., the operator of the stricken power plant.
Roke is expected to heap more misery on a country that has been lashed by natural disasters this year.
Earlier this month, Typhoon Talas slammed into central Japan, killing around 100 people in the deadliest storm to hit the country for over 30 years.