When Masahito Abe looks out at the sea that killed 40 of his neighbours just over three years ago, he is certain of one thing: at some point, perhaps long after he is gone, the ocean will again unleash a terrifying wave on his village.

Like dozens of other communities along the north-east coast of Japan struck by the March 2011 earthquake and tsunami, Koizumi is now a wasteland. Grass and weeds grow where homes once stood. On the beach, a man digs for shellfish near the remains of a solitary gutted building.

No one will return to live in the low-lying neighbourhood of Koizumi in Miyagi prefecture, home to 60% of the 19,000 people who died in the disaster. But if the government gets its way, this abandoned strip of land will be made tsunami-proof as part of a £5bn plan to defend 230 miles of coastline with hundreds of towering concrete walls.

The scale of the project, referred to by detractors as the Great Wall of Japan, is staggering even by the standards of a country where much of the coastline is already protected against storms and erosion by concrete walls.

Under government plans, hatched months after the disaster, 440 walls are to be built in the worst-hit prefectures of Fukushima, Miyagi and Iwate. But while Japan's construction industry relishes the prospect of a huge payday courtesy of its allies in the governing Liberal Democratic party, opposition among residents is gathering momentum.

"We want the government to change the shape of the coast, and redesign it so a tsunami would have minimal impact, not just build a lot of walls," said Abe, a primary school teacher in Koizumi who moved his family to a hilltop 20 years ago in anticipation of a deadly tsunami.

Masahito Abe points to the proposed site of a sea wall in the tsunami-hit village of Koizumi, north-east Japan. Photograph: Justin McCurry for the Guardian

Debate over the sea wall has proved so divisive among the village's 1,800 residents – now spread out among eight temporary housing complexes – that some fear it will derail attempts to revive the village three years after the disaster wiped it from the map. "I don't want the sea wall issue to divide people here," said Yoshitaka Oikawa, a local assembly member. "I can see the debate is already weakening their determination to rebuild their village together."

By the end of the year, Koizumi's displaced will have moved into homes being built in an area carved into a mountaintop two miles from the coast. The 14.7-metre (48ft) wall below will do little more than protect rice paddies, at a cost of $230m. "It's madness," said Abe, who wants the area to be an eco park.

Yet many of his former neighbours appear content to leave tsunami defences in the hands of the authorities. "The attitude seems to be that if the walls have already been planned and budgeted for, why interfere?" Abe said.

Christian Dimmer, an assistant professor in the urban studies department at Tokyo University, shares Abe's concerns, but believes many residents were left with little choice when offered premium rates for their land by the government. "In Koizumi there are people who are happy to sell their land for seawall construction," he said. "[They thought] they couldn't do anything else with their land and needed the money to rebuild their lives elsewhere."

Those campaigning against the wall have few allies. Yoshihiro Murai, the governor of Miyagi, is in favour, while the prime minister, Shinzo Abe, told a recent residents' forum that walls offered the best protection against a tsunami. His wife, Akie, has cautiously allied herself with the sceptics, warning of the damage so much concrete could do to ecosystems and tourism.

The 3,000 people of Fudai village owe their lives to a 15-metre wall that was dismissed as a waste of money when it was built, at the then mayor's insistence, in the 1980s. But it was the exception. Most sea walls provided inadequate protection against the March 2011 tsunami. In Kamaishi, the waves simply smashed through the city's sea wall, then the largest in the world. Concrete barriers offered little or no resistance, and may even have caused deaths among people lulled into thinking they were safe.

"Sea walls have the potential to save lives wherever they are built, provided the tsunami does not exceed the simulated height and runup pressures," said Dimmer. "The problem is that you can't predict how high the next tsunami will be, so sea walls can never give you 100% security. There will always be a risk, no matter how high you build them."

Campaigners estimate that it will take Japan's taxpayers a quarter of a century to pay the bill for sea wall construction, which could eventually cover 9,000 miles of the country's coastline. But the debate is about more than cost. Until each locality decides whether to proceed with the plan, no construction can begin on sites considered vulnerable to tsunamis.

"I don't want the rest of the world to think of Japan as a concrete fortress," said Abe. "The tsunami was a force of nature, so I can forgive it for the destruction and misery it caused. But for humans to ruin their own environment … I can never forgive that."