With a declining population, Japan is on track to lose about half its workforce by 2060, and with that, its status as an economic superpower.

Some are calling for an "immigration revolution" but that is gaining little traction in a country that is seen as the most homogenous in the world.

In Japan, birth rates are at record lows and the ageing population at record highs.

Now, the former head of Tokyo's Immigration Bureau, Hidenori Sakanaka, is calling for what many Japanese find unthinkable, large-scale immigration.

"We need an immigration revolution to bring in 10 million people in the next 50 years, otherwise the Japanese economy will collapse," Mr Sakanaka said.

He said it was now a case of "populate or perish" and Japan had to change its mentality.

"Japan is an island country and we didn't let foreigners enter for over 1,000 years, so we haven't had great experiences living with other ethnic groups," he said.

Japan's last experience with immigrants did not end well.

To fuel Japan's "economic miracle", Brazilians of Japanese descent were encouraged to return in the 1980s and 1990s.

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With their very different culture, they established communities and worked in factories, but when the bubble burst and companies downsized, many of the 300,000 Brazilians were sent home.

Shoko Takano stayed and set up a school to support the Brazilian community.

Most of the children are third or fourth generation but still cannot get Japanese citizenship.

"Japanese Brazilians are disadvantaged and they get bullied," Ms Takano said.

"The kids can't speak Japanese well so they're bullied. They become dropouts and the job prospects are not good. The community is behind from the very start."

Foreign worker visas pose problems

The Japanese government has said the solution to the shrinking workforce is to give more foreigners, working and training visas for three to five years.

But the United Nations has likened the scheme to slavery where the workers have no rights and are paid little.

A Bangladeshi man, who wants to remain unidentified, worked in the Japanese construction industry for decades but was forced out. He said he was discriminated against.

"The Japanese workers told me they didn't want to work with me or learn from me even though I have a lot of experience. I couldn't go on," he said.

His lawyer, Shoichi Ibusuki, said more visas for foreign workers was not the answer. About 200 Japanese companies had already been found guilty of mistreatment.

"The government has to create a proper system to accept foreigners and understand them more. They're using a distorted system and foreign workers' human rights are being violated," Mr Ibusuki said.

Mr Sakanaka agreed, saying Japan needed a permanent solution to the problem, not a quick fix.

"This is ridiculous. After considerable effort they learn skills and the language in Japan and then they have to go home after five years," he said.

"I think it won't last and it should be abolished. The government has to have real immigration."

For continued prosperity, Japan faces a choice: embrace immigration with full rights or lose its position as the world's third biggest economy.