Just weeks after they rode the wave of euphoria to Olympic victory when Tokyo won the right to host the 2020 Games, organisers are being brought back to Earth with a bump.
The eye-catching architectural centrepiece -- a futuristic, bike-helmet-shaped stadium -- is too big say detractors. What's more, others add, it's too expensive.
"A huge building is not always loved by people... and after the Olympics are over, many people will be forced to see it," said Fumihiko Maki, an award-winning Japanese architect responsible for one of the new towers for the World Trade Center complex in New York.
The proposed stadium, designed by London-based Iraqi architect Zaha Hadid, is intended to occupy the spot in west Tokyo of the present national stadium, an area with numerous parks and a large Shinto shrine.
Rising to about 70 metres (230 feet), the 80,000-seat facility would tower over most of the structures around it in a part of the densely-packed city that has historically restricted the height of buildings to 15 metres or less.
That would make it visible from all over the west of Tokyo, including from the immaculately-kept National Shinjuku Gyoen Park, a green lung tucked underneath the skyscrapers of Shinjuku.
"It's important that people don't have to see it if they don't want to," said Maki. "If there is no event going on inside the stadium, it is just an enormous object."
The 85-year-old has pedigree in Olympic projects; he was one of the architects in the run-up to the 1964 Games, Japan's coming out party as a modern, industrial nation.
"When we built the Tokyo Metropolitan Gymnasium (in 1954) just next to the planned new stadium, there were strict regulations to protect the landscape there," said Maki, referring to the building for which he won the Pritzker Architecture Prize.
The comments by Maki came after Japan's minister in charge of the Olympics said last month the estimated cost for the construction of the stadium is now about 300 billion yen ($3 billion), more than double the 130 billion yen that was originally stipulated in the design competition.
Hakubun Shimomura told parliament: "We need to look at how we might shrink the plan because the budget is too big."
Tokyo governor Naoki Inose has said the metropolitan government has no intention of riding to the rescue for a stadium that can be built for a maximum 150 billion yen.
Maki said Friday he plans to submit a petition to the education and sports ministry demanding complete transparency on the project.
"We don't oppose hosting the Olympics per se... I only hope the plan will get cut down to make it a smaller structure," he said.
"Unlike fireworks festivals and costume parties, an architectural building remains there for 50 years, 100 years, regardless of your likes and dislikes. The financial burden might fall on us citizens," he said.
Fellow architectural heavyweight Kengo Kuma said he shared Maki's concerns but was sympathetic to Hadid.
Kuma said Tokyo had to meet certain conditions set down by the International Olympic Committee in order to win the 2020 Games. One of those was that the stadium had to be able to hold 80,000 spectators.
"The size of the stadium ...is not so fitting" in a limited area surrounded by green parks, he told a news conference. "But this is not her fault," he said.
The placing of Hadid's stadium reflects the lessons Tokyo learned from its unsuccessful bid to host the 2016 Games, said Kuma, a Tokyo University professor.
Then, the plan had been to site the centrepiece facility in Tokyo's bay area, which has more room for a large structure.
But that "was criticised by the IOC (International Olympic Committee)... because it was separated from central Tokyo," he said.
"But central Tokyo has only space in this zone, so that's why they put it there.
The design brief "had very high hurdles. And I think Zaha Hadid's idea, the design itself, is not so bad. She tried to solve the conditions in a smart way."
Kuma warned that the time for chopping and changing was rapidly running out.
"We need to think about what we can do, because we only have seven years left, which is not a lot of time for construction on a big project like this."