He signed with the World Wrestling Federation for the first time in his career. In early 1990 Sato along with former rival Pat Tanaka were introduced to the WWF as The Orient Express by manager Mr. Fuji. During this run, Sato introduced the Sitout Powerbomb to mainstream American wrestling for the first time. The Orient Express kicked off a prolonged feud with The Rockers that started at WrestleMania VI and continued off and on for well over a year. The Orient Express got involved in the Legion of Doom / Demolition because Mr. Fuji managed both teams. Demolition was being phased out and the Orient Express took on the Legion of Doom instead. The Legion of Doom / Orient Express feud was extremely onesided due to the Legion of Doom’s massive size advantage.
After WrestleMania VI Tanaka and Sato only made two Pay Per View appearances while in the WWF. Firstly at SummerSlam 1990 where the team were defeated by ”Hacksaw” Jim Duggan and Nikolai Volkoff. Secondly as part of the Sgt. Slaughter led team “The Mercenaries” (that also included Boris Zhukov. Sato was pinned by Butch Miller 1:46 into the match and Tanaka was pinned by Tito Santana only moments later, 2:13 into the match.
Sato would return in 1991 to team with Tanaka and “Kato" for a series of 6-man tag-team matches on various WWF house show, but Sato left the WWF after only a handful of matches together.
Sato retired from in ring competition around 1992/1993 but did return to the WWF in late 1994 as the white faced manager Shinja who advised Hakushi during his heel run with the company. When Hakushi turned face, Shinja was quietly written out of the storyline and Sato retired to focus on non-wrestling ventures. His last TV appearance was on the July 24, 1995 edition of Raw, when he was piledriven by Bret Hart.