Mammoth Sasaki

Early life
Before professional frestling Yoshinori's first athletic competition took place in high school as he got into sumo wrestling. He became a third-rank junior champion while participating against kids his own age, and at the age of 16 in 1990 would begin training to become a professional sumo wrestler. In January 1993, Sasaki made his official debut wrestling as a sumo wrestler but did not gather much success right away as he would be ranked the second lowest in the sport at one time. While in sumo, his love pro wrestling never stopped as he would wear a t-shirt of his favorite promotion FMW to the ring for one of his sumo matches. Sasaki would end up improving greatly by 1995 and make it to the the fourth highest division in Sumo the Sandanme division. He would also become Akebono's assistant during his time in Sumo.

In September 1995, while training for a match, Sasaki would end up injuring his right ligament which doctors would say would put him out of any kind of action for 9 months. Sasaki would make a return but the injury along with how difficult the Sandame division was would be too much for Sasaki as he would only manage to be 2-5 before declaring his retirement from sumo in November 1996 at the age of 22 with an overall career record of 57-52-31. Sasaki would then decide that he would take a risk and try and get into the sport he loved ever since he was a young kid feeling that this would be his last chance at getting into professional wrestling. Sasaki would enter the FMW Dojo in April 1997 and would outshine everyone else in the facility being labeled the top wrestler in the dojo and would outrank future friend Naohiko Yamazaki and would also in the dojo would earn the nickname "Mammoth" for his size and strength.

Frontier Martial-Arts Wrestling (1997-2002)
FMW would feel it was time for Sasaki to be making his debut soon, but he would first participate in a exhibition match against Nobuyasu Anesaki on November 15, 1997 on an FMW show. Sasaki would get the win and it was time for him to officially to make his debut. December 8, 1997 at the Aichi Okazaki Gym, Sasaki would finally make his debut against Koji Nakagawa in the opening match of the show and although Sasaki would lose to Nakagawa after submitting to the STF it would be the beginning of his new career as a professional wrestler. On December 13, 1997 at the Kawasaki Club Citta, Sasaki would face off against Nakagawa again with Nakagawa making Sasaki submit to the Sharpshooter to the man that was training him in the Dojo. On December 22, 1997 at Korakuen Hall, Sasaki would make his Korakuen Hall debut losing to Mr. Pogo in the opening match after Pogo would hit a Body Scissors on Sasaki.

On January 7, 1998 at Korakuen Hall, Sasaki would face off against Super Leather for ZEN's show and would use techniques that he had learned in Sumo but Super Leather would be too big and experienced and would end up easily putting Sasaki away with a Tombstone Piledriver.

On September 29, 1998 Sasaki would team up with Atsushi Onita against fellow Team Zero members Tetsuhiro Kuroda and Hideki Hosaka with Hosaka forcing the referee to stop the match on Sasaki to give the win to Kuroda and Hosaka. Also on the show, Mr. Pogo # 2 would end up losing to the original Mr. Pogo forcing him to lose his name and go by the name Gosaku instead. On November 20, 1998 Sasaki would originally be scheduled to compete in a handicap match with Gosaku and Hideki Hosaka against Atsushi Onita in what would be Onita's last ever FMW match. The match would end up getting changed to Onita defeating his old rival Mr. Pogo instead. Onita would call Hosaka, Gosaku, and Sasaki to the ring to give them some words with Sasaki having to hold back tears as his leader would be leaving and ending Team Zero in FMW as a result. On December 11, 1998 Sasaki would make his second Korakuen Hall main event as he would team up with Atsushi Onita for the last time in over 14 years for Onita's start up USO promotion. Sasaki and Onita would take on fellow members of Team Zero in Tetsuhiro Kuroda and Hideki Hosaka in a Street Fight with Onita getting the pinfall over Hosaka for the win and the official end to Team Zero as Onita would disassociate himself from all the members of the group after the match. On January 5, 1999 Hideki Hosaka would break his alliance with the Team Zero group by turning on Gosaku and Sasaki after Sasaki would take the fall against Nanjyo Hayato, Flying Kid Ichihara, and Naohiko Yamazaki after Sasaki would submit to Yamazaki's Fujiwara arm bar in a humiliating loss for Sasaki. Gosaku would also end up leaving FMW shortly afterwards and Sasaki would soon become the ring assistant for Tetsuhiro Kuroda as Kuroda would begin moving up the ladder in FMW.

On May 5, 1999 Sasaki would wrestle the biggest match of his singles career at the time as he would face off against All Japan's Takeshi Morishima in a near 10 minute match before being hit a Scrap Buster and pinned by the future NOAH GHC Heavyweight Champion. Following the show, Sasaki who had been aligned with Masato Tanaka and Tetsuhiro Kuroda would join up with them as they would align themselves with Hayabusa and the FMW side against Kodo Fuyuki and his Team No Respect group. On August 25, 1999 Sasaki would get his first ever chance at a Championship Title as he would team with Tetsuhiro Kuroda and Hisakatsu Oya and challenge for Kodo Fuyuki, Koji Nakagawa, and Gedo's WEW 6 Man Tag Team Championship which would end Gedo end up getting a Gedo Clutch on Sasaki for the pinfall as they would escape with their belts.

On March 27, 2000 Sasaki would team with Naohiko Yamazaki and with H subbing for Mr. Gannosuke who could not make the show against Koji Nakagawa, Jado, and Gedo for the WEW 6 Man Tag Team Championship with would end with Jado pinning Yamazaki after a Lariat. Despite the loss, it was about time that Sasaki would finally manage to break away from the undercard to the maincard. On April 11, 2000 the push for Yoshinori Sasaki would start as he would easily defeat Flying Kid Ichihara who he had lost to so many times years earlier with a Mammoth Buster. It would be announced that on the next show that Sasaki and Hosaka would challenge for the right to become the first ever WEW Hardcore Tag Team Champions. On April 25, 2000 Sasaki would win his first ever title in wrestling as he and Hideki Hosaka would go on to beat Kintaro Kanemura and Willie Takayama to become the first ever WEW Hardcore Tag Team Champions. The new team of Hideki Hosaka and Yoshinori Sasaki would be scheduled to defend the titles against ECW's Balls Mahoney and New Jack on May 5, 2000 at FMW's anniversary show but that match would not end up taking place.

On May 5, 2000 the FMW-ECW relationship would end up coming to an end after ECW due to politics and as a result New Jack and Balls Mahoney would not show up. FMW would get The Samoans instead to challenge for the WEW Hardcore Tag Titles with the match would turning into a bloody brawl with all four wrestlers fighting all over the building with the ending coming when Sasaki getting pin after choke slamming Fatu for the win and to walk away from the biggest show of the year for FMW still the WEW Hardcore Tag Team Champions. On May 28, 2000 at Korakuen Hall, Sasaki and Hosaka would defend their WEW Hardcore Tag Titles once again after defeating Michael Shane and Ruben Cruise after Hosaka would pin Shane. In the main event of the show, Mr. Gannosuke would defeat H and Tetsuhiro Kuroda with Kodo Fuyuki as the Special Referee. After the match, Hosaka and Sasaki would come out and turned on H. Sasaki and Hosaka would attack both H and Kuroda and as Kodo Fuyuki would announce his new group of Shoichi Arai, Gannosuke, GOEMON, Kyoko Inoue, Chocoball Mukai, Hideki Hosaka, and Yoshinori Sasaki which he would call the New Fuyuki Army.

On June 21, 2000 Sasaki and Hosaka would end up dropping the WEW Hardcore Tag Team Titles to The Samoans. In the 2000 Sasaki would then go under a name change, with his preliminary days behind him, and a new preliminary wrestler by the name of Yoshihito Sasaki debuting in FMW, it was time to change Sasaki's ring to his FMW Dojo name to Mammoth Sasaki. After that he went to trial series the Mammoth Sasaki Renaming Commemoration Trial Series 1st which he failed to win it. It was very apparent that Mammoth Sasaki was climbing up the ranks in FMW. On November 19, 2000 Mammoth would challenge for the WEW Hardcore Championship against Kintaro Kanemura in a bloody, bloody brawl that would end up with Kanemura finishing off Mammoth after hitting him with a Powerbomb on a stack of chairs to retain his title.

On January 7, 2001 Mammoth would try to smooth things over with Hosaka before their match as Mammoth would give Hosaka a cherish childhood toy Sasaki had to show his alliance with Hosaka as they would defend their WEW Hardcore Tag Team Titles against the new team of GOEMON & Onryo. During the match, while battling all over the Korakuen Hall, Sasaki would accidentally hit Hosaka with the Mammoth Home Run knocking Hosaka out and while Mammoth would go and fight with GOEMON in the crowd and try and choke slam GOEMON through a table, Hosaka would get up and Powerbomb Sasaki through the table while GOEMON would hit a Swanton on Sasaki for the three count and the WEW Hardcore Tag Titles. Sasaki had just lost his title, his tag partner, and then Hosaka would begin to smash the childhood toy he had. On January 16, 2001 Mammoth would turn on Hosaka by destroying Chocoball Mukai and then through his friendship with Naohiko Yamazaki joining former Team Zero friend Tetsuhiro Kuroda's new group Team Kuroda which would consist of Kuroda, Yamazaki, Shinjuku Shark and Azusa Kudo. The following year the promtion would close.

Wrestling Marvelous Future (2002-2005)
After the foled of FMW, Sasaki and several others would join Mr. Gannosuke Wrestling Marvelous Future (WMF) promotion. On August 28, 2002 at the WMF debut show would wrestle in the main event against Garuda with Mammoth coming out to a new techno version of the old FMW song as well as FMW t-shirt which he would take off to reveal a WMF t-shirt. Mammoth would shake Garuda's hand and hug as the two of the wrestlers that what the WMF is based off as the future of wrestling. On September 16, 2002 Mammoth would face Hisakatsu Oya but would be attacked by Mitsuhiro Matsunaga and his barbed wire baseball bat during the match due to both Mammoth and Gannosuke getting very vocal at Matsunaga about not being allowed in the WMF. Matsunaga would knock Mammoth out with the bat and set up the easy win for Oya as the referee would stop the match due to Mammoth's condition. Mammoth would ask Mr. Gannosuke who had taken duties as commissioner for the show from Hayabusa and begged Gannosuke for a match at the next WMF show against Mitsuhiro Matsunaga in a match where if Matsunaga won, then he and death matches would be accepted in the WMF, but if he lost, he would have to leave WMF for good. But it ended up to Mammoth defeting Matsunaga and staying in WMF. On October 6 Mammoth would fracture his fibula and as a result would be out for over 2 months with a cast on his leg. his return match would be scheduled for December 12, 2002 against Tetsuhiro Kuroda at WMF's Korakuen Hall show. Which he ould tying with Kuroda.In 2003 he would be proclamed the ace of WMF and following Fuyuki's death in 2003 Sasaki an several other WMF wrestlers would appere in his funeral to say goodbye to their former friend, and boss.