Yūken Iwasa starts for Sapporo Nihon Univ. High school . At the beginning of March 2013 he started in an FIS race for the first time, on September 27 and 28, 2014 he made his debut in Râșnov in the FIS Cup , where he finished 24th and 20th. His next competition participation was also his debut in the Continental Cup . This took place on January 16 and 17, 2015 in his hometown of Sapporo and he finished 25th and 41st. His best placement in the Continental Cup so far was a third place at the competition in Kuopio on August 20, 2016. This was also his first Podium in the Continental Cup. To date, he has also won a total of two competitions in the FIS Cup.
In his native Sapporo, he made his debut in the World Cup in February 2017 . After successfully qualifying, he achieved 30th place on the first day of the competition and thus his first World Cup point. In the same month he was able to achieve second place at the Winter Asian Games in Sapporo from the large hill behind his compatriot Naoki Nakamura and from the normal hill behind his compatriot Yukiya Satō and also won the team competition with these and Masamitsu Itō.