Yagi made his international debut at the Four Hills Tournament 1978/79 . He achieved his best placement with rank 15 in Innsbruck . On December 27, 1979, he made his debut in the newly created Ski Jumping World Cup . In Cortina d'Ampezzo he immediately achieved a very good fifth place. In the following Four Hills Tournament in 1979/80 he just missed his first podium of his career in Garmisch-Partenkirchen as fourth. Only a few days later he celebrated his only World Cup victory and a second place in the second jumping in his homeland in Sapporo .
In the World Cup he reached third place again in March 1980 in Štrbské Pleso and finished fourth in the overall World Cup ranking. In the 1980/81 season Yagi started with an eleventh place in the opening competition of the Four Hills Tournament 1980/81 in Oberstdorf . But after the lack of great successes as in previous years, he only competed in the jumping competitions in Sapporo and Planica after the tour and ended the season in 57th place overall.
In the following season he did not find his way back to his old strength. At the Nordic World Ski Championships in Oslo in 1982 , Yagi also only had to be satisfied with lower placements. After further poor performance, Yagi ended his career with the start at the 1984 Winter Olympics in Sarajevo . There he jumped from the normal hill to rank 55 and from the large hill to rank 19.
Japan
