[5] On May 17, 2012, Miyahara made his Mexican debut for International Wrestling Revolution Group (IWRG), when he represented a team of Japanese wrestlers in the 2012 Copa Higher Power.

[3] In February 2013, Miyahara entered a storyline, where he turned on Sasaki and the former Kensuke Office, now known as Diamond Ring, by joining the villainous Voodoo Murders stable.

[14] On November 14, Voodoo Murders held a press conference to announce that Miyahara was also leaving the stable to fully concentrate on working for AJPW.

[16] The following month, Miyahara and Shiozaki made it to the finals of the 2013 World's Strongest Tag Determination League, but were defeated there by Evolution (Joe Doering and Suwama).

[1] On March 18, Miyahara received his first shot at AJPW's top title, the Triple Crown Heavyweight Championship, but was defeated by the defending champion, Akebono.

[18][19] On August 16, Miyahara won his first professional wrestling title, when he and Kotaro Suzuki defeated Keisuke Ishii and Shigehiro Irie to win the All Asia Tag Team Championship.

[21][22] Miyahara and Suzuki's reign as the All Asia Tag Team Champions ended in their second defense on January 3, 2015, when they were defeated by Dark Kingdom representatives Mitsuya Nagai and Takeshi Minamino.

[23][24] On March 27, Miyahara received another shot at the Triple Crown Heavyweight Championship, but was defeated by the defending champion, Xceed stablemate Go Shiozaki.

[29] Following the win, Miyahara announced his intention of becoming the youngest Triple Crown Heavyweight Champion in history, challenging Akebono to a title match.

At 26 years and 350 days, Miyahara became the youngest Triple Crown Heavyweight Champion in history at the time, beating the previous record held by then 29-year-old Terry Gordy.

[43][44] On February 21, Miyahara failed in his bid to become a "Quintuple Crown Champion", when he and Jake Lee were defeated by Zeus and Bodyguard in a match for the World Tag Team Championship.

[53] On November 27, Miyahara defeated Suwama in the main event of AJPW's first show in Ryōgoku Kokugikan in three years to make his sixth successful defense of the Triple Crown Heavyweight Championship.

[54][55] The following month, Miyahara and Jake Lee won their block in the 2016 World's Strongest Tag Determination League with a record of four wins and one loss, advancing to the finals of the tournament.

[66] On August 27, Miyahara defeated Ishikawa at AJPW's 45th anniversary event in Ryōgoku Kokugikan to regain the Triple Crown Heavyweight Championship.

Miyahara captured the Triple Crown for a third time on March 25, 2018, at a show at the Saitama Super Arena Community Hall by defeating Joe Doering.

Miyahara participated in the 2018 World's Strongest Tag Determination League along with Yoshitatsu, both of them would make 10 points, winning 5 matches and losing 5, failing to advance to the finals.

After being dethroned from the Triple Crown, Miyahara would compete mainly in the tag division, teaming with the likes of Jiro Kuroshio, Francesco Akira and Yoshi Tatsu from March up until August.

This would climax with Miyahara & Kuroshio unsuccessfully challenging the Violent Giants (Suwama & Shuji Ishikawa) for the AJPW World Tag Team Championship belts on August 30.

Into November, the team would take part in the 2020 AJPW Real World Tag League, and would accumulate a score of 10 points, with two losses and five wins, including the tournament final against Jake Lee & Koji Iwamoto on December 7.

[74] On January 23, 2022, Miyahara defeated Ryuki Honda in a tournament final to win the vacant Triple Crown Heavyweight Championship for the fifth time.

On March 21, Miyahara, Yuma Anzai and Ryo Inoue faced Kitamiya, Inamura and Kinya Okada in a losing effort, ending their feud.