Yuko Kondo began his mixed martial arts career in 1996 with Pancrase. Until 2000, Pancrase had different rules from the current ones. In particular, it was forbidden to strike with a fist to the head. Therefore, many bouts were reduced to pure wrestling. However, there was only one weight class - open. Kondo, who was not physically impressive, was nonetheless quite successful, defeating such fighters as Sammy Schilt and Frank Shamrock, and his first defeat came by decision in his ninth fight.
In 1997 and 1999 Kondo won the Pancrase title, also called "King of Pancrase". He was also a contender for the title in 1998. On August 31, 2003, Kondo faced a title fight against American Josh Barnett, who outweighed the Japanese by 25 pounds. Barnett's superiority in size paid off: in the third round, Kondo surrendered by rear-naked choke. After that, he stopped performing at open-heavyweight, moving up to light-heavyweight division.