Making the transition to mixed martial arts before most of his native colleagues, he started to take part in shootfights the same year of his debut.

However, after retaining his double championship before Jun Kasai, Hidaka and Homicide, he shocked pundits by vacating it and moving up to heavyweight division.

Though a tough perspective, it wasn't fruitless, as Sakata won the NWA Intercontinental Tag Team Championship with Masato Tanaka from Shinjiro Otani and Takao Omori.

As part of this faction, Sakata was placed in matches against fellow MMA fighters from the Monster Army like Kevin Randleman and Dan Bobish, sometimes teaming up with Shamoji Fujii.

However, his momentum came to an end after Sakata received a knee injury (kayfabe) by Kawada, which stunted his performance; this made them lose the titles against Erika and Margaret, as well as the finals of the Hustle King Memorial tournament.

In order to recover from those failures, Wataru introduced himself as a candidate to the new general manager job, which he shockingly won after a fan poll, and also enlisted the help of former GM assistant RG.

In early 2007, after being repeatedly beaten down by Tiger Jeet Singh, Wataru finally came to his senses and re-joined the Hustle Army, bringing Ryoji Sai with him.

Although Wataru got outclassed and was about to be finished off, his wife Eiko intervened and weakened Esperanza with her magic powers, which allowed Sakata to hit him with a superkick and pin his foe.

In 2008, Sakata participated in the Hustle Grand Prix, in which the winner could ask a wish inside the company, in order to wish for the disbandment of the Monster Army.

Depressed, Sakata left the company and secluded himself in a nattō field in order to meditate, later returning as a masked superhero-like character named Nattoman.