At least 350,000 people are still living in evacuation centres in northern and eastern Japan, many of them short of food and other essentials.
Police say more than 9000 people are now known to have died in the earthquake and tsunami on 11 March and at least 13,000 people remain unaccounted for.
Some aid from foreign countries has started to arrive and the government has started the process of finding temporary housing from other parts of the country, the BBC reports.
Workers in the north-east have also begun erecting prefabricated metal boxes with wooden floors as temporary homes.
Almost 900,000 households are without water.
Search team leaves Japan
An Australian Search and Rescue team sent to Japan following the earthquake and tsunami has flown home to Sydney.
The 72-member squad from New South Wales spent 10 days in the disaster zone, looking for survivors beneath the rubble of collapsed buildings, the ABC reports.
The Australians worked alongside teams from New Zealand and Switzerland.
New South Wales Fire Commissioner Greg Mullins says the team was constantly monitored for radiation, which was found to be within acceptable levels.
The 52-strong New Zealand Search and Rescue team returned from Japan on Sunday.