She joined the Nichibo fiber spinning company right out of high school, first playing for corporation's Ashikaga (Tochigi) team, later for the one from Kaizuka (Osaka).

Kasai and her team mates débuted at the 1960 FIVB World Championship in Brazil, finishing behind the Soviet Union.

Two years later, the Japanese won the World Championship title, defeating the Soviet squad before a Moscow audience.

When volleyball made its Olympic début in Tokyo, they lived up to high expectations by again beating the Soviet Union in the final round-robin match, in straight sets.

After the Olympics, team captain Kasai met with the Japanese prime minister and complained to him that she had not been able to find a husband because of the difficult training regimen.