There is a simple riposte to anyone who doubts an Olympics can truly transform a city: Tokyo. When Japan’s capital first won the right to host the Games, in 1959, it suffered from a desperate shortage of housing and functional infrastructure – and the lack of flush toilets meant most waste had to be vacuumed daily out of cesspits underneath buildings by “honey wagon” trucks. But within five years Japan’s capital had undergone such a metamorphosis that visitors to the 1964 Olympics responded with stunned awe.

“Out of the jungle of concrete mixers, mud and timber that has been Tokyo for years, the city has emerged, as from a chrysalis, to stand glitteringly ready for the Olympics,” the Times’ correspondent swooned, citing a long list of buildings and accomplishments “all blurring into a neon haze … that will convince the new arrival he has come upon a mirage”.

Q&A What is Guardian Tokyo week? Show Hide As Japan's capital enters a year in the spotlight, from the Rugby World up to the 2020 Olympics, Guardian Cities is spending a week reporting live from the largest megacity on Earth. Despite being the world's riskiest place – with 37 million people vulnerable to tsunami, flooding and due a potentially catastrophic earthquake – it is also one of the most resilient, both in its hi-tech design and its pragmatic social structure. Using manga, photography, film and a group of salarimen rappers, we'll hear from the locals how they feel about their famously impenetrable city finally embracing its global crown

But Tokyo’s makeover was real. There were 100km of freshly laid highways, a new sewage system, new luxury hotels and 21km of monorail from the new international airport to downtown. Meanwhile, the new Tokaido Shinkansen bullet train blasted to Kyoto and back at world-record speed, and startlingly modernist arenas such as the Tokyo metropolitan gymnasium, which was shaped like a flying saucer, only added to the futuristic wonderland vibe.

Facebook Twitter Pinterest New freeways are rush-built in 1963 in Tokyo ahead of the following year’s Olympics. Photograph: AP

There were also technological innovations. Computers were used for the first time at an Olympics, along with timing devices that could separate competitors to one-hundredth of a second. And the Syncom III satellite, combined with cutting-edge Japanese technology, enabled live TV pictures to be beamed across the globe – another first. No wonder it was hailed as the “science fiction” Olympics.

Tokyo 1964 was, according to David Goldblatt in his excellent book The Games, “the single greatest act of collective reimagining in Japan’s postwar history”. And there was a clear message for the wider world too, reflected in the choice of Yoshinori Sakai, born in Hiroshima on the day the atomic bomb was dropped on the city, to light the Olympic flame. The 19-year-old athlete was not only a symbol of his country’s rebirth following the second world war – but also its hope for a brighter future.

Such was the event’s success that it has set the bar dazzlingly high for Tokyo 2020. Every Olympian knows, after all, that while winning a gold medal is a formidable task, repeating the trick years later is tougher still. On the 24th floor of the Harumi Triton Y building, organisers finalising plans for next year’s Olympics and Paralympics say the world will see the “most innovative” Games in history.

Not everyone, to put it mildly, is as upbeat.

‘At that point blood drained out of his face’

Shortly after Japan won the right to host the 2020 Games, the country’s prime minister, Shinzo Abe, toured the Queen Elizabeth Park in Stratford, London, with Sebastian Coe, who had steered the hugely successful 2012 Olympics. There was only one thing on Abe’s mind: money.

“The only question he kept asking was: ‘How much was that? How much was that?’” Lord Coe recalls. “He loved the velodrome, which he thought was a beautiful building architecturally. I also explained the difficulties we had with the Olympic Stadium because we couldn’t get football engaged and he said: ‘Oh yeah, I get that.’

Facebook Twitter Pinterest Kengo Kuma’s under-construction New National Stadium, intended to ‘restore the link that Tokyo lost with nature’, in 2018. Photograph: AP

“Then he pointed at the Aquatics Centre and said: ‘And that one?’ I told him that was the most expensive and that Zaha Hadid had designed it. At that point blood drained out of his face and he said: ‘She’s done our new Olympic stadium.’”

By 2015 Hadid’s plans for the stadium, which had spiralled to £1.3bn, had been cancelled – and a new design by Kengo Kuma, blending steel and layers of latticed larch wood and intended to “restore the link that Tokyo lost with nature”, chosen instead. But while it is hundreds of millions of pounds cheaper, the Olympics and Paralympics remain a money pit. Last year Japanese government auditors predicted the Games would cost around £19.5bn – close to four times more than originally forecast in 2013.

To make matters worse, the president of the Japanese Olympic Committee, Tsunekazu Takeda, was forced to step down in March following corruption revelations about the bid, first revealed by the Guardian in 2016. Tokyo might be about to throw the greatest sporting party of them all. But, some of its residents ask, at what cost?

‘It is important to showcase our robot technology’

So what will Japan get for its investment next summer, aside from eight shiny new arenas?

In their office in Tokyo’s bay area, organisers stress that the Olympics and Paralympics will be “a catalyst for social change” – particularly by improving attitudes and facilities towards disabled people and opening up the country more. That makes sense. Japan remains the world’s third largest economy, but that position is in jeopardy due to a growing shortage of workers and an ageing population.

Another key aim for Tokyo 2020 is for it to be the “recovery and reconstruction Games”, following the Tohoku disaster in 2011, when an earthquake and tsunami led to over 10,000 deaths and a meltdown at the Fukushima nuclear power plant. “Baseball and softball matches will be held in the disaster-affected areas,” says Masa Takaya, spokesman for the Tokyo 2020 organisers, “and restore vitality through the power of sport.”

But these Games will be more about hearts and minds than bricks and mortar. “Tokyo 2020 is focusing more on the softer legacy,” says Takaya. “Of course we have a similar spirit as 1964 by leaving new sporting facilities. But we are even more keen to leave an intangible legacy for future generations, who will have a first-hand experience of the Games with a massive number of people with different backgrounds, religions and languages coming together in one place.”

Some of the 1964 playbook will be dusted off, with Japan keen to show it still leads the world in tech. Toyota not only plans to showcase its driverless cars at the Games but has also designed robots for the new Olympic stadium that, among other things, can take – and then bring – food and drinks orders to spectators using wheelchairs.

Facebook Twitter Pinterest A man carries a suitcase using Panasonic’s Power Assist Suit ahead of the 2020 Games. Photograph: NurPhoto via Getty Images

Panasonic, meanwhile, has created motor-assisted power suits to allow people to carry heavy luggage with ease. And Aruze Gaming’s Arisa – a sharply dressed six-foot robot that can show passengers the way to toilets and lockers, offer directions and recommend tourist attractions, in Japanese, English, Chinese and Korean – was tested at two metro stations earlier this year.

“We are still discussing what sort of other robots can we use for the Games operations,” says Takaya. “It is important to showcase our robot technology.”

‘Tourists might enjoy it … but for citizens it will be hellish’

It certainly sounds appetising enough. But in a coffee shop near Yoyogi Park, Misako Ichimura and Kumiko Suto of the Hangorin no Kai (No Olympics 2020) activist group, paint a much bleaker picture of the Games’ impact.

Among their many concerns, they claim that the construction of the new national stadium, along with other “upgrading” projects, has led to homeless people in areas like Shibuya and Shinjuku being forcibly removed from parks and streets. They also express dismay that nearly 300 residents were evicted from 10 public housing projects near the stadium to make way for luxury buildings.

“Many of these people were elderly residents living alone, and around 10 passed away just before or soon after their cruel removal from their homes,” says Ichimura. “Public housing is being destroyed in favour of high-end housing, but no new projects are going up to offset these displaced people. To make matters worse, the government has also pushed the homeless tent communities out of Meiji Park.”

Facebook Twitter Pinterest A homeless couple in Ueno Park, Tokyo. Photograph: Look/Alamy Stock Photo

Activists also have concerns about health and safety at construction sites that were backed up by The Dark Side of the Tokyo 2020 Summer Olympics, a recent report by the global trade union federation Building and Wood Workers’ International. It documents how low pay, overwork and poor access to grievance procedures have created a “culture of fear” among construction workers – and says some workers have been required to work up to 28 days in a row on Olympic projects.

There are unwelcome echoes of the past here. Before Tokyo 1964, safety standards were so low that “that there were more than 100 deaths and 2,000 injuries on Olympic-related projects”, according to Goldblatt, while the beggars and vagrants who made their homes in Ueno Park were also swept aside.

Meanwhile, Ichimura says many residents are dreading next summer. “Schools and other events are being cancelled or having altered schedules,” she says, “and the already difficult summertime transportation will be much more crowded and hot. Tourists might enjoy a happy and fun experience but for citizens it will be hellish.”

Not all criticism of the Games comes from leftwing social activists. Makoto Yokohari, a professor at the department of urban engineering at the University of Tokyo, says that while he agrees that the Games needs to promote soft legacies, he hasn’t seen any sign of them yet.

Facebook Twitter Pinterest Sunrise at the Yoyogi national gymnasium in 1964, designed by Kenzo Tange. Photograph: Art Rickerby/Getty Images

“The Olympics may merely be a snapshot event which may become like an illusion within a couple of years,” he says. His criticisms carry weight given he serves on the urban planning and sustainability panel as a part of the 2020 Tokyo Olympics/Paralympics Organising Committee. “I’m afraid my thoughts are shared by most members,” he says.

Meanwhile, the respected architect Hiroshi Ota has another criticism: Tokyo 2020 is not daring enough compared with 1964, when buildings such as Kenzo Tange’s Yoyogi gym were immediately seen as design masterpieces. As the Times put it at the time: “The arenas have approached new heights of architectural imagination and efficiency. In the the press room journalists look over blankly over their typewriters at each other. They still feel stunned as they try to pay tribute.”

That, says Ota, will not be happening in 2020. “I am not optimistic,” he says. “Most of the design for the new venues were chosen in closed competition and, more generally, I really think Tokyo has missed the chance to include people in urban planning and regeneration.”

Rising temperatures Facebook Twitter Pinterest Pedestrians cross a street during the 2018 Tokyo heatwave. Photograph: Kazuhiro Nogi/AFP/Getty Images

There is, however, one thing on which everyone agrees: the potential for Tokyo to be unbearably hot next July and August. The city’s governor, Yuriko Koike, concedes it is the one thing that keeps her up at night, saying: “Obviously climate change is a global issue, and it needs to be tackled globally, but the possibility of extreme temperatures in 2020 is a concern for me.”

Her fears are well-founded. Last year Japan suffered from a month-long heatwave that saw temperatures peak at 41.1C – the highest ever recorded in the country – and caused the deaths of 138 people. However, Koike says the city has put in place a series of measures that will ensure the Games are bearable for athletes and spectators.

“We are introducing heat-blocking road surfaces that can reduce the temperature of the road by eight degrees,” she says. “This is being installed in more than 100km in the city centre and this covers the marathon course. We have also have low-tech responses that have existed since the Edo period [1603-1868], such as water sprays.”

Lord Coe is better placed than most to understand the journey cities go through after winning an Olympic bid.

“There have been some challenges which I think Tokyo 2020 would be the first to admit,” he says. “There is permanently a dynamic of stress and tension in the buildup to a Games, and always four or five car crashes along the way.

“The first big crunch comes with costs – because you always find stuff that you can’t possibly know when making a bid. Then you end up in that odd period where everything that is going wrong in the country is down to the Olympic Games. Yet eventually the excitement will start to build, especially when you start talking about torch relays and volunteers and things that engage the public.”

Slowly these wheels are starting to turn. Last month nearly 5 million Japanese registered with the official ticketing site, more than double the initial target. And Koike insists she sees parallels with the London 2012 Games, where a modest build-up gave way to an outpouring of sustained joy and exhilaration for both the Olympics and the Paralympics.

Tokyo 2020 may have suffered so far from the same vaguely underwhelming feeling that Japan itself has laboured under since the nation’s firework-like rise after the second world war. Yet come next July, Koike and millions of others will be watching a torchbearer climb the steps of the Olympic Stadium during the opening ceremony of the Games of the XXXII Olympiad – hoping that out of the darkness of the Tokyo sky comes raging and sustained illumination.

Guardian Cities is live in Tokyo for a special week of in-depth reporting. Share your experiences of the city on Twitter, Facebook and Instagram using #GuardianTokyo, or via email to cities@theguardian.com