He's made a career playing henchmen and underlings in thousands of Japanese samurai movies, always in the role of the kirareyaku, a swordsman whose job is to die spectacularly on film. Now, at the age of 71 and after a reputed 50,000 on-screen deaths, Seizo Fukumoto has won a prize for his first ever lead role in a semi-autobiographical movie.

The veteran actor plays an ageing samurai stuntman in Uzumasa Limelight, which references his own career as one of the country's best known kirareyaku. The performance won Fukumoto the best actor prize at the Fantasia International film festival in Montreal and the movie won the Cheval Noir for best film.

"I still can't believe this," Fukumoto reportedly said after winning the award. "I do not feel like myself. I still feel like I'm being deceived."

A spokesman at Toei Studios Kyoto, where part of the film was shot, told the Wall Street Journal the actor was so humbled that he considered declining the prize.

Fukomoto has played the kirareyaku in samurai movies and television shows stretching back to the 1960s. He began acting at the age of 15 in the Japanese equivalent of Hollywood, Kyoto, and is now considered one of the nation's top exponents of the role. The actor's signature move is the "ebi-zori"or "prawn bend", which involves arching of the back, twisting and convulsing during a screen death. Fukomoto says he invented it to give himself extra screen-time, because the convulsion results in the kirareyaku's face being turned to the camera just before he falls to the ground.

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In 2012, veteran Japanese fight choreographer Mitsuhiko Seike explained why Fukumoto had risen to the top of his game in an interview with America's National Public Radio (NPR). "As a fight choreographer, I always turn to Fukumoto to act in crucial scenes," he said. "It's not just his technique, but his expressiveness. He always adds value to my choreography."

Fukumoto says he was inspired to become a kirareyaku after watching Charlie Chaplin's pratfalls in early silent movies. He soon developed dozens of different ways to die, sometimes screaming as the blood poured from his wounds, sometimes kneeling and expiring in silence.

"Whenever we die, we have to do it in a way that is unsightly or clumsy, not graceful," Fukumoto told NPR. "In this buzama we find beauty. To die in an uncool way is the coolest."

The actor was brought to the attention of western audiences in the 2003 Tom Cruise film The Last Samurai, in which he portrayed the Silent Samurai. He has also played policemen and yakuza in more modern fare. Fukumoto is said to have died on camera 50,000 times, though he himself has said the true figure is far lower.

Seizo Fukumoto, left, acted in The Last Samurai with Tom Cruise. Photograph: Warner Bros

In Uzumasa Limelight, the actor stars as an ageing kirareyaku who takes a young ingenue under his wing. "I kept refusing the offer initially, telling them I couldn't do it. It was a crazy idea," said Fukumoto of the role in an interview with the Wall Street Journal earlier this year. "I was nervous once the filming started as well. I'd never had so many cameras set up right in front of me and focusing only on me."

Fukumoto also won a special prize from the Japanese film academy in 2004. The Fantasia international film festival came to an end on 7 August in Montreal following three weeks of screenings.