Following his departure from NJPW in late 2017, Yamamoto became a freelancer, and started working most notably for All Japan Pro Wrestling (AJPW), who he signed full time for between 2020 and 2023.

With a sports background in boxing and jujutsu, Yamamoto passed an audition held by New Japan Pro-Wrestling (NJPW) in September 2001 and began training professional wrestling at the promotion's dojo the following March.

[7] Yamamoto participated in the 2004 Young Lion Cup where he defeated Hirooki Goto, Akiya Anzawa, and Hiroshi Nagao to earn a total of six points, not enough to qualify for the finals.

[12] Yamamoto teamed up with Manabu Nakanishi to compete in the 2006 G1 Tag League, defeating Giant Bernard and Travis Tomko to earn their sole victory in the tournament.

[16] On November 2, 2007 Yamamoto wrestled his last match for NJPW, teaming with his mentor Yuji Nagata in a losing effort against Tomohiro Ishii and Toru Yano.

[17] In late 2007, Yamamoto was signed by World Wrestling Entertainment (WWE) to a full-time contract, which meant that he had to relocate to the United States.

[28] Tatsu won a 26-man battle royal in the dark match to open WrestleMania XXVI by last eliminating Zack Ryder.

The following week on Raw, Tatsu and Henry received a shot at the titles in a fatal four-way elimination tag team match, which also included The Usos and Santino Marella and Vladimir Kozlov.

He returned on the September 6 episode of NXT, where he debuted black tights emblazoned with Kanji characters and the Japanese flag, his small lock of blond hair dyed red and half his face painted.

In his final WWE pay-per-view appearance, Tatsu unsuccessfully competed in the Andre the Giant Memorial battle royal at WrestleMania XXX in April 2014.

[46] At BELIEVE 79, Yamamoto defeated Aaron Epic to win the SCW Florida Heavyweight Championship, his first professional wrestling title (which he vacated on March 28, 2015 due to his neck injury).

On September 20, 2014, Yamamoto made his debut for Chikara, losing to Ashley Remington via disqualification, following outside interference from Juan Francisco de Coronado.

[47] On October 13, 2014, at King of Pro-Wrestling, Yamamoto, billed as Yoshitatsu, returned to New Japan, attacking Jeff Jarrett when he interfered in the main event match and, in doing so, helped Hiroshi Tanahashi defeat A.J.

[56] On March 22, NJPW announced that Yoshitatsu would wrestle his NJPW return match on April 10 at Invasion Attack 2016,[57] where he, Hiroshi Tanahashi and Michael Elgin defeated Bullet Club's The Elite (Kenny Omega and The Young Bucks (Matt Jackson and Nick Jackson)) to win the NEVER Openweight 6-Man Tag Team Championship.

However, neither Elgin nor Tanahashi accepted Yoshitatsu's invitation to join the stable, which led to Captain New Japan stepping up as the first member of the new group.

[60][62] Yoshitatsu, Elgin and Tanahashi made their first successful title defense on April 23 against the Bullet Club trio of Bad Luck Fale, Kenny Omega and Yujiro Takahashi.

[64] On September 12, Yoshitatsu, upset with Captain New Japan's poor performances, announced a Twitter poll that would decide whether he would get to stay in Hunter Club.

[66] After starting a feud with Captain New Japan, now renamed "Bone Soldier", Yoshitatsu announced on November 5 that he had recruited Billy Gunn as his new Hunter Club partner for the 2016 World Tag League.

[69] In February 2017, NJPW sent Yoshitatsu to their Mexican partner promotion Consejo Mundial de Lucha Libre (CMLL) for a tour.

[71] On September 12, 2017, Yoshitatsu made his debut for All Japan Pro Wrestling (AJPW), entering the annual Ōdō Tournament and defeating Tajiri in his first round match.

[74] He entered the 2017 Real World Tag League with Miyahara and had a good showing, winning five matches, but was one short of a finals berth.

[77] After nine successful title defences and a record breaking 587 days as champion, Yoshitatsu lost the Gaora TV Championship to Jun Kasai in a tables, ladders and chairs match on January 3, 2021.

His most notable match came on June 26 where he defeated former Oriental and Pacific Boxing Federation champion boxer turned mixed martial artist Yōsuke Nishijima.

[79] On July 22, he won the AJPW TV Six-Man Tag Team Championship with Carbell Ito and Seigo Tachibana from Tajiri, Yusuke Kodama and Hokuto Omori.

[84] On September 30, a masked wrestler caused a three-way match to end in a no contest between former Good Looking Guys members Jack Morris, Anthony Greene and LJ Cleary, after he attacked the referee.