Championships fights and joined Pro Wrestling Zero-One as a freelancer. His wrestling ventures increased over time, and he finally joined Zero-One full-time. Sakata started teaming up with fellow RINGS wrestler Hirotaka Yokoi, but his greatest highlights came from his solo career, winning the Tenka-Ichi Junior Tournament after big wins over Ikuto Hidaka, Low Ki, Dick Togo and Naohiro Hoshikawa. The tournament gained him the vacant WORLD-1 Junior Heavyweight Championship, and he later defeated Low Ki again for the NWA/UPW/Zero-One International Junior Heavyweight Championship, which solidified his status as the new junior ace of the company. 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. Hustle In 2004, Sakata started appearing in off-beat wrestling "opera" federation Hustle due to its business relationship with Zero-One. After a match in his home promotion, Sakata was approached by Private Shimada and offered a place in Generalissimo Takada's villainous Monster Army, but Wataru rejected the offer and gave Shimada a tombstone piledriver, announcing he was going to join babyface faction Hustle Army instead. 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, Sakata was later put in a hair vs. hair match against Umanosuke Anjo and was defeated, being forced to shave his head, which took its toll on his morale. Declaring himself to be unworthy of the Hustle Army, he ran away from the stable and instead worked to be accepted in Monster Army, but he was rejected after losing to Toshiaki Kawada in his entrance test. Now free, Sakata teamed up with other unaligned wrestlers like Mark Coleman, Takehiro Murahama and Ryoji Sai, which he called unofficially "Sakata Army". His team grew stronger, winning the Hustle Tag Team Championship from Genichiro Tenryu and Tadao Yasuda and later adding Tenryu himself when Sakata lost a match to him and asked him to be the stable's advisor. Wataru also gained the support of Yuko Aoki as his valet for a time after saving her from a beatdown by general manager Hiroko Suzuki. However, his momentum came to an end after Sakata received a