Media were shown inside the $1.25 billion stadium on Wednesday, 387 days before the opening ceremony will be held at the same venue, Reuters reported.
The 60,000-capacity stadium, which will also host the athletics and soccer events during the Games, was designed by Japanese architect Kengo Kuma and aims to embody Japan’s connection with nature.
Wood collected from all of Japan’s 47 prefectures has been used to build the stadium’s iconic slated roof, and the seats, 45,000 of which have been installed, are a mix of green, brown and white to reflect trees growing.
The final preparations are being completed before an inauguration event in front of the public on December 21.
“The work for this stadium has been going on for three years and we have five months to go,” said National Stadium Development Director Takeo Takahashi.
“About 90 percent of the construction work has been completed and, as you can see, almost all the buildings have been completed.
“We are now working on the interior and facility equipment inside the stadium.
“The grass and track have yet to be laid but this is expected to be completed in the next month.
The Olympic Stadium is one of eight new venues to be used at Tokyo 2020, all of which are on schedule for completion.
The Musashino Forest Sports Plaza, a venue to be used at Tokyo 2020 but not built specifically for the Games, was opened in November 2017 while the newly-built archery and rowing venues have recently opened.
The canoe slalom venue is set to be unveiled on Saturday whilst construction continues at the Aquatics Centre, which is 75 percent complete, the Gymnastics Centre and Ariake Arena, which will host volleyball and wheelchair basketball next July.
The first apartments are also being completed at the Olympic and Paralympic village, with Tokyo 2020 organizers saying 88-92 percent of all residential buildings are finished.
There will be 18,000 beds available at the village during the Olympics, 12,000 of those for athletes, and 8,000 available during the Paralympics.