He served as a crew member on board the International Space Station for Expedition 54/55, and returned to Earth on June 3, 2018.

In 2011, Kanai served as cavenaut into the ESA CAVES[3] training in Sardinia, alongside Thomas Pesquet, Tim Peake, Sergey Ryzhikov and Randolph Bresnik.

[4] In August 2015 JAXA announced his selection to the crew of Expedition 54/55 to the International Space Station, scheduled for launch in December 2017.

[6] In January 2018 Kanai received publicity after mistakenly tweeting that he had grown "as much as 9 cm" taller due to the absence of gravity.

A 9 cm growth spurt might hypothetically create problems, as the Soyuz spacecraft to take astronauts back to Earth has a limit on seating height.