Osaka Prefectural Gymnasium
In 1982, Seidokaikan held its first All-Japan Knockdown Open tournament. This initial event attracted over 3,500 people to the Osaka Prefectural Gymnasium. Over the next several years the Seidokaikan All-Japan Open tournament became a showpiece in Western Japan, and by 1989 the tournament was attracting over 8,000 fans, bringing competitors from more than 20 styles of karate.