The punishment, familiar from a thousand Japanese gangster films, is known as yubitsume, or finger-cutting, and serves as a demonstration of the offender’s sincerity and his tolerance of agonising pain.

But this week a new twist in the grisly tradition came to light when a Tokyo doctor was arrested for overseeing a finger-chopping ritual under local anaesthetic — and claiming it on the health service.

The doctor, Shin Ki Tae, a South Korean, administered the anaesthetic at his clinic to a Japanese businessman who had gone bankrupt, leaving him in debt to Kyoji Kakutani, a gangster who had invested in it. After Mr Kakutani amputated the finger with a hammer and chisel, Dr Shin popped the digit into a bottle of formaldehyde, handed it to its former owner, and charged the whole thing to the Japanese health system.

“I couldn’t reject his request,” the doctor told the police, according to Agence France-Presse. “If (the gangster) did it by himself, it would make a big mess at my clinic and I didn’t want that to happen.” Dr Shin was arrested on Monday on charges of aiding and abetting a criminal.

According to the National Police Agency of Japan, there are about 80,000 yakuza, most members of three big gangs, the Inagawa-kai, in the Tokyo region, the Sumiyoshi-kai, in central-western Japan, and the mighty Yamaguchi-gumi, based in the city of Kobe.

In a society otherwise remarkably free of crime, the gangs have a near-monopoly on violence, which they direct largely against one another. As long as they do no harm to the civilian population, they are treated with tolerance by the police, who allow them to run bars, sex businesses, loan-shark operations and protection rackets with little interference.

As well as smuggling drugs, the yakuza expanded during the 1980s into superficially legitimate businesses, including property, construction and waste disposal.

Yakuza organisations have their origins in medieval guilds of gamblers and pedlars and regard themselves as the heirs to the ethics of the samurai. Especially incompetent yakuza with much to apologise for sometimes end up parting with more than one fingertip and the practice has generated a minor cosmetic industry in artificial finger joints for reformed mobsters who want to move on to new careers. The best replacements are those invented by a doctor from Bradford.

MOB RULES

Explore World News

• Iraq News

• US & Americas News

• Europe News

• Middle East News

• Asia News

• Africa News

• Ireland News

Times Recommends

• Congo's rangers risk their lives to guard gorillas
• Pearl farming in China losing its lustre
• Axl Rose mystery as album arrives at last