For a man who lost out on one of music's biggest pay-cheques, Inoue Daisuke is in fine form: a toothy smile spreading over the big, rough-hewn face of a natural comedian.
The good humour comes in useful for interviews like this, when he is inevitably asked if he regrets not patenting the world's first karaoke machine, which he invented in 1971. After 35 years, during which his unlikely contraption has conquered every corner of the globe, accompanied by the sound of a billion strangled, drink-sodden earthling voices, the question must sound like the whistling of an approaching bomb. But the smile stays in place.
"I'm not an inventor," says the 65-year-old in his small Osaka office, where the first version of the karaoke machine sits in a corner. "I simply put things that already exist together, which is completely different. I took a car stereo, a coin box and a small amp to make the karaoke. Who would even consider patenting something like that?"
"Some people say he lost $150m," says Mr Inoue's friend and local academic Robert Scott Field. "If it was me, I'd be crying in the corner, but he's a happy guy who loves people. I think it blows his mind to find that he has touched so many people's lives." Many in Japan now know, thanks to television specials and a 2005 movie biopic, that Mr Inoue was a rhythmically challenged drummer in a dodgy covers band in Kobe when he hit on the idea of pre-recording his own backing tracks. The band had spent years learning how to make drunken businessmen sound in tune by following rather than leading, and drowning out the worst of the damage, so Mr Inoue knew the tricks of the trade when the boss of a steel firm asked him to record a tape for a company trip to a hot springs resort.
Karaoke (literally, "empty or missing orchestra") was born. Mr Inoue and his friends gave it a leg-up by making more tapes and leasing machines to bars around Kobe. Taking the machines for a spin cost 100 yen (£1) a pop - the price of three or four drinks in 1971 - and Mr Inoue never thought it would make it out of the city.
By the 1980s, karaoke was one of the few words that required no translation across much of Asia. Communist China embraced it, and even made it a standard feature in some cars. Hong Kong sent it back to Japan as karaoke boxes, small booths where friends and family could torture each other in soundproofed bliss. Every evening across Asia, thousands of the booths judder into life on a toxic cocktail of booze and tin-eared singing. The pastime even has its own lingo. A K-King is a maestro of the small, subtitled screen. A K-Lunch an indigestion-inducing karaoke lunch. Mr Inoue, however, languished for years in international obscurity. But in 1999, after karaoke had stomped noisily into the US and Europe, Time magazine astonishingly called him one of the 20th century's most influential Asians, saying he "had helped to liberate legions of the once unvoiced: as much as Mao Zedong or Mahatma Gandhi changed Asian days, Inoue transformed its nights". "Nobody was as surprised as me," he says.
In 2004, he was given the "Ig Nobel Peace Prize" by Harvard University, a joke award presented by real Nobel winners. He received a standing ovation after calling himself the "last samurai", and attempted a wobbly version of the Seventies Coca-Cola anthem "I'd Like to Teach the World to Sing." Standing on the same stage with the man who invented the comb-over hair style, Mr Inoue was awarded an empty cereal box and a certificate, which hangs today in his Osaka office. The Nobel laureates in turn (or in revenge) murdered the Andy Williams' standard "Can't Take My Eyes Off You". Mr Inoue loved it.
"I wish I spoke English," he says. "It would make life easier, and I could go to the US again, do speaking tours and make some money." Now his life is the subject of a fictionalised movie, called simply Karaoke, currently on DVD release in Japan and starring an actor considerably better-looking than the weathered, plump drummer of 1971.
"At least they got someone tall to play me," he laughs. A typical Osaka businessman: amiable, fast-talking and with a slightly untamable air, Mr Inoue once tried working in a proper company, but baulked at wearing the salary-man's uniform, the dark pinstripe suit. "I looked like a rocker and it didn't go down very well. I wasn't cut out for that life."
He didn't use a karaoke machine until he was 59, but loves to listen to syrupy pre-1960s ballads. His favourite English songs are "Love is a Many Splendoured Thing" and "I Can't Stop Loving You" by Ray Charles. "They're easy to sing, which is good because I can't sing at all," he said.
Mr Inoue is tormented by daft questions, but takes them in his stride. "People approach me all the time and ask me if I can't help their husbands sing better, and I always say the same thing. If the singer was any good, he would be a pro and make a living at it. He's bad because he's like the rest of us. So we might as well just sit back and enjoy it."
These days, he makes a living selling, among other things, an eco-friendly detergent and a cockroach repellent for karaoke machines. "Cockroaches get inside the machines and build nests, chew on the wires," he says.
Friends say he is the ideas man, while his wife, who works in the same Osaka office, helps bring them to life. In the 1980s, he ran a company that successfully managed to persuade dozens of small production firms to lease songs for eight-track karaoke machines. But in the early 1990s, laser and dial-up technology left the firm behind. Bored and depressed, he had a breakdown, but bounced back to life thanks to his dog - "I had to look after it, and it got me out of the house". He keeps a huge portrait of a Labrador in his office and says his next business venture will involve dogs.
Not everyone, of course, thanks Mr Inoue for his invention. A recent Japanese movie called Karaoke Terror depicts a bunch of bored, middle-aged women and a group of college kids, both obsessed with karaoke, who go to war with each other, destroying a whole city. Karaoke as almost too easy a metaphor for the emptiness some see in contemporary Japanese culture.
Meanwhile, the little box Mr Inoue unleashed on an unsuspecting world shows no sign of dying. The global industry for machines and tunes continues to grow, and television shows like Pop Idol have helped a once maligned pastime become respectable. The truly dedicated can warble simultaneously with partners thousands of miles away, using the internet. Even churches are not safe - some have installed karaoke machines to improve hymn singing.
Not surprisingly, some people have reacted badly to the onslaught. Many pub landlords would rather die than hear "Bohemian Rhapsody" sung by a drunken stag party ever again, and karaoke venues around the world occasionally erupt into violence. In one of Thailand's most famous cases of karaoke rage, a Bangkok policeman shot and killed a customer after he heckled him for singing the same tune four times.
But the pony-tailed businessman believes the little box he put together in Kobe has done far more good than harm. "As something that improves the mood, and helps people who hate each other lighten up, it has had a huge social impact, especially in Japan. Japanese people are shy, but at weddings and company get-togethers, the karaoke comes out and people drink a little and relax.
"It's used for treating depression and loneliness. Go to old people's homes and hospitals around the country and there is a karaoke machine. I keep hearing of places where karaoke is huge - like Russia - and it is used as therapy. It makes people happy. When I see the happy faces of people singing karaoke, I'm delighted."
The film of Mr Inoue's life supports the idea that karaoke is socially useful. Kicking off with a grim list of suicide statistics among middle-aged Japanese men, it depicts a salary-man losing his job, wife and son after he is fired. He starts singing karaoke and finds a new purpose in life.
"We went to see the movie together," remembers Mr Scott Field. "They got these good looking actors to play him and his wife, so he was really happy. Afterwards he said: 'I get letters and e-mails from all over the world and now they've made a movie of my life story. You can't buy things like that.'"