Kimiya Yui

Kimiya Yui was born on January 30, 1970, in Nagano Prefecture, Japan, and reached space by way of the fighter cockpit. He graduated from the National Defense Academy of Japan in 1992 and joined the Japan Air Self-Defense Force, where he spent roughly 17 years as a pilot, flying the F-15 Eagle and serving as a test pilot while accumulating more than 2,000 flight hours. By late 2008 he was a lieutenant colonel working in the Air Staff Office's Defense Planning Division when JAXA selected him as an astronaut candidate in 2009, chosen from a field of 963 applicants. As the first Japanese astronaut with a military background, Yui faced a distinctive hurdle: Japanese rules kept him from simultaneously holding a military role and a civil scientific one, so he retired from the Self-Defense Force before he could fly. He trained at NASA in ISS systems, robotics, spacewalking, and survival, and became proficient in English and Russian in addition to Japanese.

Yui's first flight came in 2015, when he launched aboard Soyuz TMA-17M on July 22 and spent 142 days aboard the International Space Station as a flight engineer for Expeditions 44 and 45. The defining moment of that mission was operating the station's robotic arm to capture Japan's HTV-5 cargo vehicle, the "Kounotori," as it arrived with supplies and experiments, a demanding piece of orbital choreography that showcased both his piloting instincts and JAXA's contribution to station logistics. Throughout the expedition he ran Japanese and international scientific and medical experiments that took advantage of the microgravity environment. A decade later Yui returned to orbit as a mission specialist on SpaceX Crew-11, launching August 1, 2025, aboard the Crew Dragon Endeavour with commander Zena Cardman, pilot Mike Fincke, and cosmonaut Oleg Platonov. Serving as part of Expeditions 73 and 74, he worked in the Kibo laboratory module, contributing to experiments and technology demonstrations and taking part in public-outreach activities, until the crew returned earlier than planned in January 2026 after a crewmate's medical event prompted NASA's first medical evacuation from the station.

Across his two flights Yui has logged more than 300 days in space and roughly 7,400 hours, without performing any spacewalks himself; his signature skills lie instead in robotics and experiment operations. His career carries particular weight in Japan as a demonstration that the test-pilot path can lead to JAXA's astronaut corps, and his decade-spanning return to the ISS underscored the continuity of Japan's human-spaceflight program from the Soyuz era into the commercial-crew age. An active JAXA astronaut, Yui remains part of the agency's roster and a prominent public face for Japanese spaceflight, embodying the disciplined, methodical approach that carried him from an F-15 cockpit to the controls of the station's robotic arm.