1. Yoshinori Sasaki is a Japanese professional wrestler and retired sumo wrestler and mixed martial artist, currently working for Pro Wrestling Freedoms under the ring name Mammoth Sasaki, where he is a former King of Freedom Tag Team Champion, becoming the longest reigning champion during his second reign with the title.
Mammoth Sasaki is best known for his time with Frontier Martial-Arts Wrestling, where he competed between 1997 until the promotion's closure in 2002.
Mammoth Sasaki's first push came when he became a member of Atsushi Onita's faction Team Zero in 1998.
Mammoth Sasaki was a third-rank junior champion of sumo wrestling in his high school and began training to compete for a professional sumo career in 1990.
Mammoth Sasaki made his sumo debut in January 1993 under the ring name Wakasasaki and rose to the rank of sandanme in 1995.
Mammoth Sasaki began training for a professional wrestling career at the Frontier Martial-Arts Wrestling dojo in April 1997, where he was trained by Katsutoshi Niiyama.
Mammoth Sasaki made his wrestling debut by defeating Nobuyaso Anesaki in an exhibition match on November 15,1997.
Mammoth Sasaki was used as an enhancement talent, being used to put over the established stars of FMW during the early matches of his career.
Mammoth Sasaki resumed teaming with Yamazaki and continued to compete as a jobber to the stars throughout 1999.
Mammoth Sasaki received his first championship match at Goodbye Hayabusa II: Last Match, by teaming with Tetsuhiro Kuroda and Hisakatsu Oya against Kodo Fuyuki, Koji Nakagawa and Gedo for the WEW 6-Man Tag Team Championship in a losing effort.
At Night in Shibuya Backdraft Eve, Mammoth Sasaki won the first title of his career as he and Hosaka defeated Kintaro Kanemura and Hido to become the inaugural WEW Hardcore Tag Team Champions.
Sasaki competed in a series of three matches titled Mammoth Sasaki Renaming Commemoration Trial Series, losing all of the matches against Masato Tanaka, Hayabusa and Tetsuhiro Kuroda.
Mammoth Sasaki soon joined Tetsuhiro Kuroda's Team Kuroda with Shinjuku Shark, Naohiko Yamazaki and Azusa Kudo.
Mammoth Sasaki played a pivotal role in Kuroda's feud with Kodo Fuyuki.
Mammoth Sasaki lost the title to Kanemura in a rematch at 12th Anniversary Show.
Mammoth Sasaki chose to join Fuyuki and defeated GOEMON later at the event.
Mammoth Sasaki turned fan favorite by joining Gannosuke, Kintaro Kanemura and Tetsuhiro Kuroda to defend FMW against WAR.
On January 6,2002, the team of Gannosuke, Kuroda and Mammoth Sasaki lost to Balls Mahoney, The Sandman and Vic Grimes.
Mammoth Sasaki headlined WMF's debut show The Independence Day by defeating Garuda.
Mammoth Sasaki was pushed as the promotion's top fan favorite, feuding with the Brand Double Cross group and was eventually groomed to become the company's ace.
At WMF's 1st Anniversary Show, Mammoth Sasaki teamed with Ideka-kun and Tetsuhiro Kuroda against Hido, Mr Gannosuke and Tetsuhiro Kuroda in a losing effort.
At WMF's 2nd Anniversary Show, Mammoth Sasaki teamed with Seiya Morohashi and Tomohiko Hashimoto to defeat GOEMON, Junji Tanaka and Onryo.
In late 2004, Mammoth Sasaki participated in a round robin tournament, where he qualified for the finals by defeating Mr Gannosuke in a playoff and then lost to Soldier in the tournament final on February 20,2005.
Mammoth Sasaki began appearing at Apache Army shows in early 2005 to distance himself from WMF as he was irate at Gannosuke booking himself as the focus of the promotion.
Mammoth Sasaki debuted for Fighting World of Japan Pro Wrestling on July 31,2003 and competed a few matches for the promotion in 2003 and 2004.
Mammoth Sasaki would participate in Apache Army's round robin tournament for the vacated WEW World Tag Team Championship by teaming with GENTARO and they scored four points in the tournament before being eliminated.
On February 4,2007, Mammoth Sasaki received a title shot against Togi Makabe for the WEW Heavyweight Championship in a steel cage match, with Makabe retaining the title.
Mammoth Sasaki debuted for Takashi Mammoth Sasaki's Pro Wrestling Freedoms as a fan favorite on March 10,2010, making his return to wrestling after the accident and joining the promotion full-time.
In 2011, Mammoth Sasaki participated in the Death Match Tournament by defeating Kenji Fukimoto in a scramble bunkhouse deathmatch quarter-final and lost to Masada in a barbed wire board alpha deathmatch semi-final.
Mammoth Sasaki entered the 2013 Death Match Tournament, losing to Jun Kasai in the opening round.
In January 2014, Mammoth Sasaki was paired with Toru Suguira to participate in a tournament for the inaugural King of Freedom World Tag Team Championship.
Mammoth Sasaki received his next title shot at the tag team title with Toru Suguira against Hayata and Yuya Susumu on November 17,2016, but failed to win the title.