Saito made his pro wrestling debut in Pioneer Senshi and spent much of his early career in W*ING, a small promotion where he enjoyed moderate success.[citation needed]
After a lengthy hiatus, Saito made his surprise return to pro wrestling in October 2000 for Pro Wrestling Noah, teaming up with longtime mentor Masashi Aoyagi.[citation needed]
In 2001, he joined Jun Akiyama's STERNNESS faction as second-in-command and his career skyrocketed.[citation needed] Obtaining success like never before, he won the GHC Tag Team Title with Akiyama in September 2002, his first championship belt in his 12-year career.[citation needed] Akiyama and Saito proceeded to hold the titles for more than 8 months before losing them to Kenta Kobashi and Tamon Honda in June 2003.[citation needed]
Saito would go on to form his own stable, Dark Agents, with Takashi Sugiura, Masao Inoue and former Heisei Ishingun stablemate Shiro Koshinaka.[citation needed] He awarded himself the GHC Great Happy Christmas Championship in 2004, a title that was defended only once a year, on Christmas Eve.[citation needed] He would also challenge for the GHC Heavyweight Title on two separate occasions, in 2004 against Kenta Kobashi and in 2005 against Takeshi Rikio.[citation needed]
From March 29 to April 27, 2008, Saito and partner Bison Smith featured in NOAH's inaugural Global Tag League. The pair ultimately won the tournament defeating Mitsuharu Misawa and Yoshinari Ogawa in the final.[1] As a result, the duo became number one contenders and on May 23, 2008, Saito and Smith defeated Naomichi Marufuji and Takashi Sugiura to win the GHC Tag Team Titles.[2] The pair's first championship defense came five months later where the two defeated Jun Akiyama and Takeshi Rikio.[3] On November 28 the pair made their second defense against Akira Taue and Takeshi Morishima.[4] Shortly thereafter, Saito received a title opportunity against GHC Heavyweight Champion Kensuke Sasaki, however on December 7, Saito lost that title match.[5] To finish the year, Saito won a two-night tournament simply named 'The Tournament' where he wrestled five matches with ten-minute time limits in the two nights with the result decided by judges if the time limit was reached. Saito defeated Masao Inoue in the final where the judges ruled in his favor 5–0.[6]
As tag team champions, Saito and Smith took part in the second ever Global Tag League.[citation needed] The pair finished fourth in the eight-team block missing out on a spot in the final by only having lost to second place Takeshi Morishima and Kensuke Sasaki.[citation needed] The champions faced off with the tournament winners Mitsuharu Misawa and Go Shiozaki on June 13, however tragedy struck and, in the defense, Misawa suffered a spinal injury after a high-angle backdrop suplex from Saito and was later pronounced dead at the hospital at 10:10 p.m. JST.[7]
The pair of Saito and Smith did not defend the championships again and their next attempted defense would occur on September 21 where they would ultimately lose the titles to Morishima and Sasaki.[8] Shortly after, on September 27, Saito received another GHC Heavyweight Championship match against Shiozaki at the 'Great Voyage in Tokyo' event, which was also subtitled 'Mitsuharu Misawa, always in our hearts,' however Saito came up short in his effort to win the championship.[9]
Saito won the 2011 Global Tag League becoming the first man ever to do so twice.[citation needed] Saito and partner Jun Akiyama received their title shot on May 8 against Takuma Sano and Yoshihiro Takayama, though the pair ultimately fell short in the attempt to win the championships.[citation needed] It was reported on December 29, 2011, Saito's contract with NOAH would not be renewed after it expires in January 2012.[citation needed] After his contract expired, Saito became a freelancer.[citation needed]
On March 31, 2024, Saito won his first singles championship, the World Heavyweight Championship at ZERO1 Noto Peninsula Earthquake Charity Pro Wrestling, a house show promoted by Pro Wrestling Zero1, defeating Chris Vice.[13] At Noah Destination on July 13, 2024, Saito dropped the championship to Go Shiozaki.[14] Saito then announced his retirement from professional wrestling would take place at the end of 2024 on November 17.[15]