The Contender: The television series saw a live human at the competition awards

In 1998, a Japanese man was stripped and left alone in an almost empty apartment as part of a challenge for a reality TV show.

Tomoaki Hamatsu, known as Nasubi, was left with only a pen, a few blank postcards, a phone and a rack full of magazines.

But he wasn’t there to read. The concept of the show was to see if a human being can survive on competition prizes alone.

To win the challenge, the value of the prizes won had to reach a certain financial threshold – 1 million yen, around £6,000 at the time.

He would not emerge for 15 months after a gradual descent into depression and mania, driven by hunger and isolation. Almost three decades later, Nasubi’s ordeal is being revisited as part of a new film which has just been screened at the Sheffield Documentary Festival.

“I came across his story when I was working on another project and got lost in one of those internet rabbit holes,” recalls Clair Titley, director of The Contestant.

“But I found a lot of what I encountered was almost derogatory. Nothing really talked about Nasubi’s story in depth. (I had) all these questions, like, why did he stay there and what effect did it have on him? So I approached him with that premise, that I wanted to make a film about his experience.”

Nasubi, who had been randomly selected at an open audition, knew he was being filmed, but the explanation given to him about where the footage would go was vague and left him with the impression that it probably wouldn’t air.

In reality, the 22-year-old was slowly becoming one of the country’s biggest celebrities, as weekly updates on his progress became one of the most popular segments of variety show Denpa Shōnen.

Critics mostly hated the program, but it attracted a huge audience of young viewers.

The series began airing before the release of The Truman Show, starring Jim Carrey as a man who is unaware that his life is being broadcast as a TV series.

And it would be another year before Big Brother launched in the Netherlands, ushering in a whole new era of reality television.

But despite being a harbinger of things to come, there remains relatively little awareness of A Life in Prizes, as the segment was known, outside of its territory.

“I think people have heard more about it in the last decade because YouTube has really exploded,” Titley told BBC News. “But at the time, it was never shown outside of Japan and South Korea. It was never intended to be presented outside of that world.”

Nasubi, an aspiring comedian at the time, knew few details of what the challenge would be before starting.

He was left in the windowless room, without clothing or basic items – not even toilet paper – and had no contact with the outside world.

Contender features new interviews with both Nasubi and the producer who helmed the segment, Toshio Tsuchiya.

Other contributions come from those who were involved in its coverage – including a former BBC correspondent who was based in Japan.

But so much of the story is contained in the material itself, viewers of the documentary follow Nasubi’s progress in the same way that viewers did at the time.

Titley says she and her team went through the original shoot “thoroughly” to remove much of the original furniture.

“All the footage has been overlaid with Japanese graphics, it has Japanese narration, canned laughter, sound effects, it’s a cacophony of noise and graphics,” she explains. “So we tried to allow an English-speaking audience to understand what it was like.”

The team overlaid the Japanese graphics with English equivalents and recreated the audio as accurately as they could. An English-speaking narrator was hired to translate the original commentary.

The resulting documentary has already been released on Hulu in the US – with critics as fascinated by the story as they were repulsed by Nasubi’s attempt.

“A chronicle of a media phenomenon, a reality TV landmark, and a psychological nightmare packaged as entertainment, it’s the kind of documentary where you’re aware that what you’re witnessing is 100% true and you still can’t wrap your head around it. your brain around what you see.”

“None of the film’s retrospective interviews, as honest and thoughtful as they are, prove as riveting as the raw video of Nasubi’s ordeal,” he said.

“Titley’s film is ultimately less a commentary on an entire medium than a study of one of that medium’s most remarkable characters.”

As the show progressed, Nasubi found success in many of the competitions she entered – but the prizes she won didn’t always serve her well.

These included tyres, golf balls, a tent, a globe, a teddy bear and tickets to Spice World: The Movie.

The fact that he was getting weaker and weaker seemed a little worrying to the producers, one of whom suggests in the documentary that Nasubi might have died if he didn’t win rice in one of the awards.

Later, he also won sweet drinks and dog food, with which he survived for several weeks.

About 15 million viewers tuned in to see his victories and how he used them in his efforts to survive.

Nasubi remained naked for the entire time participating, as he never won an item of wearable clothing (his genitals are covered by a floating eggplant emoji added by the producers).

The door to the apartment was not locked and in theory Nasubi was allowed to leave whenever he wanted. So why didn’t he?

“I think there are a lot of reasons,” says Titley. “One of them is that he’s very stoic, and that’s because of where he comes from in Fukushima and his parents, who were very strict.

“He’s also a very loyal person. He didn’t want to get into trouble, and he was very young and naive. He still has incredible confidence now. And there’s also that Japanese samurai spirit: ‘I will overcome and I will endure.’ ‘.”

Nearly three decades later, Nasubi described the show as “cruel”, adding that “there was no happiness and no freedom”.

“Maybe three or five minutes a week of my life (were shown). And that was edited to highlight my happiness when I won (an award),” he told Deadline.

“Of course the viewers were like, ‘Oh look, he’s doing something fun and something he’s enjoying…’ But most of my life suffered.”

And yet, in the documentary, she doesn’t seem bitter about the experience, and Titley says her impression was that “she’s in such a positive place now.”

“When people have asked him if he has any regrets, he always says that although he wouldn’t want to do it again, he wouldn’t be the person he is (otherwise),” she says.

Nasubi was eventually freed in a Michael McIntyre-style stunt where he was taken to a new fake room before the walls collapsed to reveal that he was actually on stage in front of a live audience applaud the name.

The documentary also follows Nasubi after his release, showing his efforts to use his famous fame for good causes – ultimately giving him a sense of fulfillment.

Titley says Nasubi felt it was the right time to revise her story, adding that she “maybe found some peace with what happened.”

The duty of care practices of the 1990s are not what they are today – and viewers are unlikely to support such a format now.

But the documentary raises questions about where to draw the line when it comes to entertainment – and how much public appetite is to blame.

“I’d like people to reflect on their own relationships with social media and reality TV,” says Titley, “and how complicit we all are as viewers and consumers.”

The competitor will launch in the UK later this year.