YUI Kimiya was born in 1970 in Nagano. In 2015, he spent 142 days aboard the International Space Station as a Flight Engineer as part of the crew of Expeditions 44 and 45. During this stay, he controlled the robotics used in the capture of “KOUNOTORI5 (HTV5)” and conducted both Japanese and international scientific and medical experiments utilizing the space environment. From August 2025 to January 2026, he spent approximately 166 days aboard the ISS as part of Expeditions 73 and 74 of the Crew-11 mission. During his stay, he contributed to the advancement of human spaceflight by conducting various experiments and technology demonstrations in the Kibo module, improving the ISS communication infrastructure, and engaging in public outreach activities.