Shintaro Hayashi never expected his job to lead him to the underworld.
The prosthetics maker built a career making silicone body parts for patients with breast cancer, or legs and arms for those injured in serious accidents.
But a decade ago, he started to notice a change in the clientele at his Tokyo-based company, Aiwa Gishi.
"I started to see a gradual increase in people who were asking for prosthetic pinkies," Hayashi, 39, said. "They weren't the standard small, medium or large, but custom-made pinkies."
In Japan, a stunted pinkie signifies membership in the yakuza, or Japanese mafia. In a ritual known as "yubitsume," yakuza members are required to chop off their own digits to atone for serious offenses. The left pinkie is usually the first to go, though repeated offenses call for further severing. As a result, those who get out, have a hard time finding work because of the stigma attached to those missing fingers.
That's where Hayashi comes in.
The doctor molds silicone prosthetic pinkies, made to seamlessly mask the amputation, making for a smoother transition to the outside world. Priced at nearly $3,000 each, the fingers are carefully painted, to match the exact skin color of the client. Former yakuza members, who make up 5 percent of Hayashi's business, often keep several sets of fingers for different seasons – the light skinned version for winter, and a tanned look for summer.
Hayashi sums up his clientele in three categories: Those who are dragged into his office by girlfriends worried about their reputations, ex-members who are eager to move up the corporate ladder but worried about the repercussions of their past being exposed, longtime yakuza who have no intention of getting out, but need to cover up for a child's wedding or grandchild's sporting event.
"Many people keep a fist, to prevent detection," he said. "But there comes a point where you can't hide your fingers any longer. Some people have one joint severed, others have worse," he said.
Shigeru Takei, who asked ABC News not to use his real name, had to undergo yubitsume four times during his 20 years in the yakuza.
The first time, he had to slice the joint of his pinkie to atone for a bar fight. When one of his subordinates got caught using drugs, Takei took the fall, by severing that finger even deeper. He had to chop off another when he decided to cut ties altogether.
Takei's current wife convinced him to turn his life around after years spent in jail, but his missing fingers prevented him from landing a job.
"The first time I applied for a job, I got cut after the interview. I couldn't write the truth in my resume because I had been in the yakuza for 20 years," he said. "If you don't have fingers, there's no way to get a sales job."
Takei sought out Hayashi eight years ago after an extensive web search for a prosthetics maker, and credits his fingers for helping him turn his life around. He now works for a home makeover company and says he's only been questioned about his fake fingers once.
Takei visits Hayashi four times a year for "touch-ups," a process that involves re-painting discolored portions of the prosthetics. He's amassed more than 100 fingers over the years, and keeps extras stored away in case the silicone tears.
"I take off the [prosthetic] fingers as soon as I get home," he said. "I never wear them on my days off."
The increasing demand for prosthetic pinkies coincides with an aggressive push to crack down on the yakuza. Gang member numbers have steadily declined, since the Anti-Organized Crime Law went into effect in 1992. But there are still more than 70,000 gang members, according to the National Police Agency. In recent years, police have clamped down on cash flows, gang activities, and passed measures aimed at pressuring legitimate businesses to cut ties with the mob.
In 2012, the U.S. Treasury Department froze assets and barred transactions for the largest yakuza organization, the Yamaguchi-gumi, saying its leaders had racked up "billions of dollars" a year from crimes that include drug and human trafficking, prostitution, money laundering, and fraud.
Takei, who has been out of the underworld for nearly a decade, says the crackdown has discouraged some yakuza bosses from going through with the ritual of yubitsume, fearful the missing pinkie will make them an easier target.
Hayashi has already produced more than 300 prosthetic fingers, and revels in the transformation each one brings.
"If you put on the finger, you can turn your life around," he said.