Japanese billionaire Yusaku Maezawa said Tuesday he was "excited" ahead of his mission to the International Space Station, which marks Russia's return to space tourism.

Maezawa, a space enthusiast who made his wealth in online fashion, and his production assistant, Yozo Hirano, will spend 12 days aboard the orbital station.

Their Soyuz rocket operated by Russia's Roscosmos space agency will blast off from the Moscow-leased Baikonur cosmodrome in Kazakhstan on Wednesday at 0738 GMT.

"I feel excited. I'm like an elementary student waiting for a school trip," Maezawa, 46, said at a press conference on the eve of the launch.

Russian cosmonaut Alexander Misurkin (C), Japanese billionaire Yusaku Maezawa (R) and his assistant Yozo Hirano will take part in a mission to the International Space Station
Russian cosmonaut Alexander Misurkin (C), Japanese billionaire Yusaku Maezawa (R) and his assistant Yozo Hirano will take part in a mission to the International Space Station POOL via AFP / SHAMIL ZHUMATOV

"I want to see the earth from space. I want to float in zero gravity... (I want to see) how I will change through this experience," he said.

Maezawa and Hirano plan to document daily life on board the space station for the tycoon's YouTube channel and its more than 750,000 subscribers.

Maezawa said he has a list of 100 tasks to complete while on the ISS.

Russian cosmonaut Alexander Misurkin, who will pilot the pair's spacecraft, said the group's time on the ISS will be very busy and described it as a "challenge".

The Soyuz rocket operated by Russia's Roscosmos space agency will blast off from the Moscow-leased Baikonur cosmodrome in Kazakhstan on Wednesday
The Soyuz rocket operated by Russia's Roscosmos space agency will blast off from the Moscow-leased Baikonur cosmodrome in Kazakhstan on Wednesday AFP / Kirill KUDRYAVTSEV

The group will hold a "friendly" badminton tournament on the ISS before returning to Earth on December 20, he said. Maezawa said that he was looking forward already to eating sushi on his return.

Asked about the importance of developing space tourism, Maezawa said space is still a "world of the unknown" for mankind.

"People can have hopes and dreams (by seeing that) a regular person like me can go into such unknown world," he said.

The Japanese billionaire -- the country's 30th richest person, according to Forbes -- said going to space was his childhood dream.

"I was blessed with this opportunity and I'm truly happy I can go," he said.

Maezawa said he "trusts" Russia's Soyuz rocket that will deliver him to the ISS.

The spacecraft, decorated with Japan's flag and Maezawa's "MZ" logo, was rolled onto the launch pad over the weekend in preparation for takeoff.

On Tuesday, the rocket was blessed by local priest Father Sergiy, who has carried out Orthodox ceremonies for all spacecraft taking off from Baikonur since 1999.

"With every launch, part of my soul flies away from the launching pad with the rocket. And with every crew, part of my soul goes into space," he told AFP at his church in Baikonur.

He said this will be his 380th blessing.

"When I bless them, I take responsibility for them," he said.

Maezawa and Hirano will become the first space tourists sent by Russia in over a decade and the first from Japan to visit the ISS.

With SpaceX now able to ferry NASA astronauts to the ISS in Crew Dragon capsules, Roscosmos has seats to fill on its Soyuz launches and has been ramping up its civilian journeys this year.

In October, Roscosmos sent an actress and a director to the station where they filmed scenes for the first movie in orbit.