A few hundred protestors demonstrated against the Games outside the stadium as the ceremony began. Tokyo is battling a surge in virus cases, and is under emergency measures that means bars and restaurants must shut by 8:00 pm and cannot sell alcohol. But Olympic officials have put a brave face on the unusual circumstances, with IOC chief Thomas Bach insisting cancellation was never on the table.
"Over the past 15 months we had to take many decisions on very uncertain grounds," he said this week. "We had doubts every day. There were sleepless nights.
"We can finally see at the end of the dark tunnel. Cancellation was never an option for us. The IOC never abandons the athletes... we did it for the athletes.
There are also hefty financial incentives in play. Insiders estimate the IOC would have been on the hook for around $1.5 billion in lost broadcasting revenues if the Games had been cancelled.
The pandemic has not been the only hiccup in preparations though, with scandals ranging from corruption during the bidding process to plagiarism allegations over the design of the Tokyo 2020 logo.
The controversies kept coming right up to the eve of the Games, with the opening ceremony's director sacked on Thursday for making a joke referencing the Holocaust in a video from 1998.
Back in the sporting arenas, a new generation of Olympic stars are looking to shine after a decade dominated by the likes of Usain Bolt and Michael Phelps.
US swimmer Caeleb Dressel could target seven gold medals, and in track and field, 400 metre hurdlers Karsten Warholm of Norway and the USA's Sydney McLaughlin are among those hoping to emerge as household names.
Gymnastics meanwhile will see Simone Biles attempt to crown her dazzling career by equalling Larisa Latynina's record of nine Olympic gold medals.
New Olympic sports will also be on display in Tokyo, with surfing, skateboarding, sport climbing and karate all making their debut.
