“Japan is an anomaly among developed economies,” said Yukari Takamura, an expert in climate policy at the Institute for Future Initiatives at the University of Tokyo. “The era of coal is ending, but for Japan, it’s proving very difficult to give up an energy source that it has relied on for so long.”

Japan’s appetite for coal doesn’t solely come down to Fukushima. Coal consumption has been rising for decades, as the energy-poor country, which is reliant on imports for the bulk of its energy needs, raced to wean itself from foreign oil following the oil shocks of the 1970s.

Fukushima, though, presented another type of energy crisis, and more reason to keep investing in coal. And even as the economics of coal have started to crumble — research has shown that as soon as 2025 it could become more cost-effective for Japanese operators to invest in renewable energy, such as wind or solar, than to run coal plants — the government has stood by the belief that the country’s utilities must keep investing in fossil fuels to maintain a diversified mix of energy sources.

Together with natural gas and oil, fossil fuels account for about four-fifths of Japan’s electricity needs, while renewable sources of energy, led by hydropower, make up about 16 percent. Reliance on nuclear energy, which once provided up to a third of Japan’s power generation, plummeted to 3 percent in 2017.

The Japanese government’s policy of financing coal power in developing nations, alongside China and South Korea, has also come under scrutiny. The country is second only to China in the financing of coal plants overseas.

At the United Nations climate talks late last year in Madrid, attended by a sizable Japanese contingent, activists in yellow “Pikachu” outfits unfurled “No Coal” signs and chanted “Sayonara coal!”

A target of the activists’ wrath has been Japan’s new environment minister, Shinjiro Koizumi, a charismatic son of a former prime minister who is seen as a possible future candidate for prime minister himself. But Mr. Koizumi has fallen short of his predecessor, Yoshiaki Harada, who had declared that the Environment Ministry would not approve the construction of any more new large coal-fired power plants, but lasted less than a year as minister.