In 2013 Yui was assigned as backup Flight Engineer for Italian astronaut Samantha Cristoforetti for ISS Expedition 42/43. Cristoforetti launched onboard Soyuz TMA-15M alongside fellow Expedition 42/43 crewmembers Anton Shkaplerov and Terry Virts 23 November 2014, following which Yui began training as prime crew Flight Engineer for ISS Expedition 44/45 alongside Roscosmos cosmonaut Oleg Kononenko and NASA astronaut Kjell Lindgren.