As Tokyo’s millions put in another day’s work on the coalface of capitalism, celebrity Marxist philosopher Kohei Saito and his friends are clearing rocks from a muddy mountain stream.

Saito’s core argument — that capitalism is the root cause of climate change and we need to stop chasing growth to save the planet — has struck a chord in the world’s fourth-largest economy, especially among young people.

The associate professor at the University of Tokyo has sold half a million copies of his latest book and last month spoke at music festival Fuji Rock, headlined by The Killers.

He has become a face of the global movement for “degrowth” — a word that “kind of freaks people out,” Saito told AFP as he tended to his slice of collectively owned land on the capital’s western outskirts.

“Maybe it’s not the best way to convince people, especially in America,” said the 37-year-old, whose hit title “Slow Down: The Degrowth Manifesto” came out in English this year.

But using the term is one way to “provoke or challenge” widely accepted economic principles which are leading to environmental ruin, he said.

Saito is not a member of the Japanese Communist Party and he rejects the need for top-down, Soviet-style systems.