Three years ago, in the depths of winter, a group of young men boarded an aircraft in the windswept city of Dalian in north-eastern China and set off with high hopes of making it big by working in Japan.

Lured by stories of the good salaries and advanced skills they could gain, they had signed up to become trainees. They had paid high fees to Chinese brokers, as well as agreed to guarantees that they would meet a raft of obligations, believing they could earn many times more than they earn at home and return as heroes. “We had heard from people we knew that Japan was a good country and a good place to work and that it would be possible to save money,” says Zhou Liankhang, 30, one of those who left Dalian that day in January 2007.

But far from being a workers’ paradise, Japan has been a country of hardship and discrimination for Mr Zhou and many of his compatriots, who are often forced to work long hours in gruelling conditions for less than minimum wages. “All the dirty, dangerous work is done by the Chinese workers,” says Li Changqing, 34, who journeyed from the same city that day.