Teruko Nakazawa once intervened in a knife fight between an ex-offender and their mother -- all in a day's unpaid work for Japan's army of volunteer probation officers.

The 83-year-old, who jokes she is a "punk" as she puffs on a cigarette, devoted decades to supervising and helping rehabilitate convicted criminals on parole.

But she did not take a single yen for her hard work under a long-running but little-known state scheme that some say contributes to the nation's famously low crime rate.

"I never wanted to be thanked or rewarded," said Nakazawa, recalling once going to save a boy "surrounded by 30, 40 bad guys".

"I did what I did because I wanted to," she told AFP. "You can't help but try to put out a fire when you spot one, right?"

But the altruistic programme faces an uncertain future, with around 80 percent of hogoshi aged 60 or over.

The recent murder of a hogoshi by a parolee has also rattled the trust in ex-offenders' good nature underlying the system.

For one of Nakazawa's former charges, "she was like a grandma".

"I wouldn't dare do anything bad on her watch," he said,........

© International Business Times