LIKE giant spacecraft that have just touched down, they give the countryside an otherworldly look.
Elevated land-based islands are what one architect is proposing for the TMhoku region of north-east Japan, the area that was devastated by last March's magnitude 9 earthquake and the mega-tsunamis it triggered.
Keiichiro Sako of Sako Architects in Tokyo has created a blueprint in which groups of these islands form entire towns. They are designed to protect people living in low-lying areas from future tsunamis.
TMhoku Sky Village is not just an architect's flight of fancy: one municipality in the affected region is making moves towards building one in its locality and others could follow.
Most islands will be used for residential purposes, with between 100 and 500 houses and apartments. Fuel stations, waste disposal and storage facilities, and car parks are on lower floors. Commercial islands, meanwhile, will house factories and processing facilities for industries such as fisheries and agriculture. As well as lifting residents high above the destructive power of the waves, the design comes with a number of safety features. A reinforced gate at the back of each island automatically closes after a tsunami warning, while steps up the sides let people climb to safety.
Power is off-grid, from renewable energy sources including wind and solar, to ensure supply following a disaster. Lithium-ion batteries act as backup. The islands' oval shape is also important. Flat surfaces take the full force of a body of water, but an oval one allows water to flow around.
Each three-storey island would offer 90,000 square metres of usable space and be bolted deep into the bedrock via vast steel pillars. The exterior walls are made of 50-centimetre-thick reinforced concrete, while utility spaces on the bottom floor are compartmentalised in a radial formation for even stress distribution - rather like the spokes in a bicycle wheel.
At the centre of each cluster of islands would be the administrative area, home to municipal offices, schools, businesses and leisure facilities. The ambitious plan also features the world's first indoor marina to protect the local fishing fleet.
Other large-scale projects for rehousing the TMhoku people are in the pipeline, such as one by renowned architect Toyo Ito - designer of the 2002 Serpentine Gallery Pavilion in London - that employs a modern take on traditional architecture but built on higher ground. Another includes apartments built into the base of mountains.
However, while Ito's concept involves the relocation of entire towns, Sako's makes it possible for people to return to the land where they lived before.
"Moving to higher ground, officially recommended after the disaster, would mean a huge change for residents in the region, many of whom rely on the sea and land for their livelihood," says Sako. "The aim of the project is to not only preserve communities, but to make them safer to inhabit."
Critics point to the complex issue of how the reconstruction will be funded. Yasuaki Onoda of the Department of Architecture and Building Science at TMhoku University says that while the idea is sound, estimated costs of 20 billion yen (£160 million) per island are prohibitive.
To mitigate these costs, Tohoku Sky Village will recycle debris from the disaster for use in some building components. Sako also believes the islands will become a tourist attraction.
But there is one more possible obstacle: the people. Masayuki Wakui, a professor of architectural design at Tokyo Metropolitan University, believes that given the futuristic look of the islands, the "conservative" nature of people in TMhoku may pose a problem.
"It's questionable that they will take to it easily. But if there are communities that decide they do not want to relocate but want to stay on the plains, this is a feasible option."