He was one of the most successful ski jumpers of the late 1960s and early 1970s. In 1970 he was runner-up on the normal hill behind the Russian Gari Napalkow at the Nordic World Ski Championships in Vysoké Tatry, Czechoslovakia . In 1971/72 he won the first three jumping competitions at the Four Hills Tournament and would have taken the overall victory, perhaps even as the first athlete to win all competitions, which Sven Hannawald only succeeded in 2001/02. Before the last competition in Bischofshofen , however, Kasaya (like the entire Japanese contingent) had to return to Japan on the instructions of the team leadership to prepare for the 1972 Winter Olympics , which took place in Sapporo , Japan . There he won the gold medal on the normal hill and became a Japanese national hero - the silver and bronze medals also went to Japan. Since the Nordic World Ski Championships were being held at the same time as the Olympic Games at that time, Kasaya became world champion on the normal hill with his victory. When jumping on the large hill on February 11, 1972, he was in second place after Wojciech Fortuna after the first run , but he failed the second round - also due to bad wind conditions - so that he fell back to 7th place in the classification.