佐竹雅昭
Nakasako made his professional kickboxing debut on May 24 at the K-1 Braves '98 event in Fukuoka. In a dominant effort, he earned a TKO victory over taekwondo champion Pierre Guenette. Three months later, he reached the finals of the K-1 Japan Grand Prix '98 tournament before suffering his first defeat: a majority decision loss to former world champion Masaaki Satake. Losses Stan Longinidis and Andy Hug followed, but Nakasako rebounded with wins over world champion Dewey Cooper and Muay Thai exponent Tofan Pirani. He reached the semifinals of the K-1 Spirits '99 and K-1 Andy Memorial events, but endured decision losses to Nobu Hayashi and Musashi, respectively.