Kazuyoshi Ishii began his karate training in 1969 with Kyokushin Kai under the legendary Kancho Hideyuki Ashihara in Shikoku, Japan. By 1980 the gifted Ishii had opened dojos in Osaka, Kobe, Nara, Kyoto, Okayama, Himeji and Sakai City, and had become the leader of all of the Ashihara Kyokushin dojos in the Western Japan (Kansai) region.

By blending the innovative and unparalleled teachings of Mr. Ashihara with the power karate style of Kyokushin, and by adding his own technical system and characteristic philosophy, Mr. Ishii founded a new style under the International Practical Karate Federation Seidokaikan. The goal of this new style was to help young people study karate and budo philosophy, and to provide them a method of improving their health and to develop a strong spirit and body. Accordingly, the name chosen for this new organization was "Seidokaikan" - which literally translated means "Correct Way" Martial Arts Hall.

Seidokaikan karate incorporates traditional budo philosophy and modern sports karate training methods. It is designed to develop the individual mentally, spiritually and physically by increasing strength, endurance, and the ability to prevail in competition and/or self-defense situations.

In 1980 Mr. Ishii opened various university dojos in Japan and formed the All-Japan Student's Karate Federation and the New Japan Karate Federation Seidokaikan. In 1981 Kancho Ishii opened the Seidokaikan World Headquarters in Kita Ward in Osaka Japan. Mr. Ishii's top student at this time was Shihan Takeo Nakayama. Nakayama had achieved fame by taking second place in the Kyokushin All-Japan tournament as a green belt.

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

The organization began international involvement in 1983 by accepting a challenge from Hong Kong Kung Fu, and celebrated victory at a match held at the Queen Elizabeth Stadium. At this event Kancho Ishii performed a demonstration for Hong Kong Television.

In June of 1983 the organization published a karate technical manual entitled "Practical Seido Karate". The following month the first of a four part educational video series "Practical Seido Karate" (the first of its kind in Japan) was produced.

That same year Kancho Ishii performed a demonstration on Japanese National Television with Benny "the Jet" Urquidez, and in 1984 he regularly appeared on television in Japan to demonstrate his brand of karate.

In June of 1991 4,500 people crowded into Tokyo's Yoyogi Hall to watch a 5 on 5 challenge match between Seidokaikan and World Oyama Karate.

Later that same year Kancho Ishii produced the Karate World Cup which brought together fighters from around the world to compete in a Grand Championship tournament in Japan. Toshiyuki Atokawa won this tournament.

In July of 1991, Kancho Ishii's "Katsu Tame no Karate" (Winning Karate) book was published. It soon became the best selling sports book in Japan. The companion video was also popular.

1992 was another key year for Seidokaikan. In March the Karate Olympics I show was held at the Tokyo Gymnasium and the Karate Olympics II show which attracted Switzerland's Andy Hug (who had also achieved fame as the World Runner Up at the Kyokushin World Tournament) was held at Tokyo's Yoyogi Hall. That year the Karate World Cup tournament attracted many more international stars. Hug won the World Cup and later appeared in other professional karate bouts against fighters such as Shidokan's Ryuji Murakami and Seidokaikan's Nobuaki Kakuda who both were knocked out.

By 1994 other prominent Kyokushin fighters such as Michael Thompson of the U.K. and Australia's Sam Greco joined Seidokaikan and have also focussed their attention on the professional arena.

1993 saw the birth of the K-1 Grand Prix series which can be regarded as Kancho Ishii's professional "chef d'oeuvre". This event series has grown into the biggest professional stand-up fighting event in the world. In Japan K-1 regularly sells out at the major dome venues and has become a major sport which commands prime time network television broadcast appeal. The 1998 the K-1 Grand Prix Finals at the Tokyo Dome was seen live by over 65,000 fans. The K-1 event has been successful in Europe and in 1998 the series held its first K-1 USA Grand Prix show in Las Vegas, Nevada.

Kancho Ishii always expresses his commitment to Budo and karate spirit as an event producer and cautions that we must never forget the roots of K-1 that lay in Seidokaikan. Since 1996 the Karate World Cup has been suspended and the annual All-Japan Tournament has become a "Budo Festival" to return to the spirit of karate and the Japanese philosophy of Budo.