Sasaki also competed in MMA and won both fights by submission, remaining undefeated in mixed martial arts competition.

During his time in Canada, he won the Stampede International Tag Team Championship in August 1989, with All Japan loyalist Sumo Hara.

He won his first major title, the WCW United States Heavyweight Championship on November 13, 1995, defeating Sting at a NJPW Event.

Finally at the end of the month, he captured the IWGP Heavyweight Championship by defeating long reigning champion Shinya Hashimoto, winning three major honors in a one-month span.

He won the G1 Climax for the second time in August 2000 with a victory over last year's winner Manabu Nakanishi in the final, now holding both of New Japan's two heavyweight singles crowns.

In March 2001, Sasaki lost the IWGP Heavyweight Title to Scott Norton and in late 2002 he resigned from the promotion after a falling out with company management.

He became the only WMG Heavyweight Champion; however, tensions between him and Choshu over financial issues caused Sasaki to withdraw and the company to die a slow death.

After introducing his student Katsuhiko Nakajima and forming the Kensuke Family group, Sasaki began a redemption storyline where he attempted to win back the support of both the wrestlers and fans in NJPW.

[6] By October, Sasaki was once again a firm fan favourite, and regained the IWGP Heavyweight Championship in controversial fashion, beating Kazuyuki Fujita in just 2:29 after reversing a sleeper into a pinfall.

After returning to NJPW, Sasaki once again started wrestling for AJPW too as a freelancer, entering the 2004 Champion Carnival and making it to the final where he lost to Keiji Mutoh.

On January 16, he unsuccessfully challenged Toshiaki Kawada for the Triple Crown Heavyweight Championship,[12] but saw success throughout the year, first winning the Champion Carnival by beating Jamal in the final.

[13] On July 26, Sasaki and his student Katsuhiko Nakajima then beat the Voodoo Murders ("brother" Yasshi and Shuji Kondo) to win the All Asia Tag Team Championship.

TV Triple Arrow Six Man Tag Team Cup, beating the Voodoo Murders (Kondo, Yasshi and Taru) in the final.

After losing the Triple Crown titles in 2008, he jumped to Pro Wrestling Noah and announced he would make it his full-time home promotion, while still operating the Kensuke Office.

Sasaki and Morishima finished the league with a total of four points, losing out to A-Block winners Yoshihiro Takayama and Takuma Sano.

[3][17] Following Sasaki's retirement, Diamond Ring was left with only one remaining wrestler, Katsuhiko Nakajima, with Satoshi Kajiwara resigning and Mitsuhiro Kitamiya joining Pro Wrestling Noah.

He has two fights under his belt, winning both by submission in the first round beating Dan Chase in 2001 and future UFC fighter Christian Wellisch in 2003.

[19] In November 2002, he was originally scheduled to fight Minoru Suzuki, but due to injury, he pulled out and was replaced by Jushin Thunder Liger.

During this period, he would alter his look, cutting his signature mullet (he would occasionally dye his hair different colors), wearing ring gear bearing the word, "Volcano", and adapting moves he learned in MMA training to expand his pro wrestling moveset.