A crowd at the launch site—including Maezawa's family and friends—braved freezing temperatures and cheered as the rocket blasted off into the grey sky, leaving a trail of orange flames before disappearing in the clouds.
"This has been a long process. It's so moving. I was about to cry," said Ryo Okubo, 46, a lawyer for Maezawa's space projects.
"I'm really excited but he's also my friend so I'm worried about him," a longtime friend of the billionaire, 44-year-old Hiroyuki Sugimoto, told AFP.
Among the revellers was a family-of-three who won spots at the launch from out of a million applicants. The brother and sister were holding hand-drawn banners with Maezawa's face inside a sunflower and a picture of a rocket.
After docking at the Poisk module of the Russian segment of the ISS, the trio will spend 12 days on the station. The Japanese tourists will document their daily life aboard the ISS for Maezawa's popular YouTube channel.
The 46-year-old billionaire has set out 100 tasks to complete on board, including hosting a badminton tournament in orbit.
The ISS is home to an international crew of seven people including two Russian cosmonauts and a Japanese astronaut.
Maezawa, who is a space enthusiast, also plans to take eight people with him on a 2023 mission around the moon operated by Musk's SpaceX.
He and his assistant are the first private Japanese citizens to visit space since journalist Toyohiro Akiyama travelled to the Mir station in 1990.
Before its hiatus from the industry, Russia had a history of shepherding self-funded tourists to space.
In partnership with US-based company Space Adventures, the Roscosmos space agency previously took seven tourists to the ISS since 2001—one of them twice.
Competing with SpaceX
The last was Canada's Cirque du Soleil co-founder Guy Laliberte in 2009, who became the first clown in space.
"It's been 12 years. We've had to be very patient. We've had to be very creative. So, this is the culmination of a lot of effort from a lot of different people," Tom Shelley, president of Space Adventures, told AFP shortly after liftoff.
In October, Russia launched its first untrained cosmonauts into space since that trip, delivering a Russian actress and director to the ISS where they filmed scenes for the first movie in orbit.
Moscow had stopped sending tourists to space after NASA retired its Space Shuttle in 2011, which left Russia with a monopoly on supplying the ISS.
NASA bought up all Soyuz launch seats for a reported $90 million per spot—effectively ending tourist flights.
That changed last year when a SpaceX spacecraft successfully delivered its first astronauts to the ISS.
NASA began purchasing flights from SpaceX, stripping Russia of its monopoly and costing its cash-strapped space agency millions of dollars in revenue.
While the cost of tickets to space for tourists has not been disclosed, Space Adventures has indicated that they are in the range of $50-60 million.
Roscosmos has said it plans to continue growing its space tourism business, already commissioning two Soyuz rockets for such trips.
"We will not give this niche to the Americans. We are ready to fight for it," Roscosmos director Dmitry Rogozin said following the launch Wednesday.
But Roscosmos is facing competition from SpaceX in space tourism too.
Earlier this year, a Crew Dragon capsule took an all-civilian mission on a three-day trip around the Earth's orbit in a historic first.
Also hot on Russia's heels are Amazon founder Jeff Bezos's Blue Origin and billionaire Richard Branson's Virgin Galactic, which completed their maiden tourist voyages this year.
© 2021 AFP