全日本柔道選手権大会
Ishii won the gold medal in Olympic Judo at the Beijing 2008 Summer Olympics, a silver medal at the 2006 Asian Games and two All-Japan Judo Championships representing Japan. Ishii made his professional MMA debut at "Dynamite!! 2009" losing to fellow Judoka gold medalist Hidehiko Yoshida by unanimous decision, but currently holds a record of 24-12-1. Ishii is currently under contract with Professional Fighters League. A professional mixed martial artist since 2009, Ishii has also competed for Rizin Fighting Federation and Bellator, and is the current HEAT Heavyweight Champion and SBC Heavyweight Champion.