KATOKU (Kagoshima) • Standing on its mountain-fringed beach, there is no hint that the Japanese village of Katoku even exists. Its handful of houses hide behind a dune covered with morning glory blooms and pandanus trees, the chitter of cicadas interrupted only by the cadence of waves and the call of an azure-winged jay.

In July, the beach became part of a new Unesco World Heritage Site, a preserve of verdant peaks and mangrove forests in far southwestern Japan that is home to almost a dozen endangered species.

Two months later, the placid air was split by a new sound: the rumble of trucks and excavators preparing to strip away a large section of Katoku's dune and bury inside it a two-storey-tall concrete wall meant to curb erosion.

The sea-wall project shows how not even the most precious ecological treasures can survive Japan's building obsession, which has long been its answer to the threat of natural disaster - and a vital source of economic stimulus and political capital, especially in rural areas.

The plan has torn the village apart as residents fight deeper forces remaking rural Japan: climate change, ageing populations and the hollowing-out of small towns. The project's supporters - a majority of its 20 residents - say the village's survival is at stake, as it has been lashed by fiercer storms in recent years.

Opponents - a group of surfers, organic farmers, musicians and environmentalists, many from off the island - say a sea wall would destroy its delicate ecosystem.

Leading the opposition is Jean-Marc Takaki, 48, a half-Japanese Parisian who moved into a bungalow behind the beach last year. A nature guide and former computer programmer, Mr Takaki began campaigning against the wall in 2015, after moving to a nearby town to be closer to nature.

The fight embodies a clash playing out in rural areas across Japan. Old-timers see their traditional livelihoods in industries like logging and construction threatened by newcomers dreaming of a pastoral existence.

Villages may need new residents to bolster their eroding populations and economies, but sometimes chafe at their presence.

When Mr Takaki first visited Katoku in 2010, it seemed like the paradise he had been seeking. "I had never seen any place like it," he said. That has all changed. If they finish building this thing, I don't know what we're going to do here."

Japan's countryside is pockmarked with projects like the one planned for Katoku. The country has dammed most of its rivers and lined them with concrete. Tetrapods - giant concrete jacks built to resist erosion - are piled along coastlines.

After the 2011 quake and tsunami that devastated Japan's north-east and triggered the Fukushima nuclear meltdown, planners rimmed the region with sea walls.

The projects are often logical for a country plagued by earthquakes, volcanic eruptions, tsunamis, landslides and typhoons, said University of Michigan's associate professor Jeremy Bricker, who specialises in coastal engineering.

The question is: "To what extent is that concrete there because of the stuff that needs to be protected and to what extent is it part of the Japanese culture?"

In some cases, concrete could be replaced with natural buffers, like supplemental sand or heavy vegetation, Mr Bricker said.

While some Japanese civil engineers are using such alternatives, he added, "Japan's been so focused on promoting work for traditional contractors - that means casting concrete - that there hadn't been as much emphasis on soft solutions".

NYTIMES