After returning to Japan, Hayashi eventually decided to join All Japan Pro Wrestling (AJPW) due to his friendship with Keiji Mutoh and established himself as one of their top stars, winning the World Junior Heavyweight Championship and both the World Tag Team Championship and the All Asia Tag Team Championship with Satoshi Kojima.
In 2006, Hayashi won the AJPW Junior League tournament.

Now under the name Miguel Hayashi Jr., Hayashi, PEPE Michinoku, and El NOSAWA Mendoza formed a team during the AJPW Champion Carnival called Mexico Amigos.
Nobutaka Araya joined the team after six-man Action between Mexico Amigos and Araya/Fuchi/Hirai at the Carnival's final show.

After multiple bouts against Minoru Suzuki, Nosawa offered Suzuki an invitation into Mexico Amigos, which he declined.
This resulted in the group changing multiple assets.
Their name was changed to Mexico Amigos Black, the previous worn Mexican Flag attire became Black and Gold attire, and Nobutaka Araya was kicked out of the group.
The groups is currently in a heated rivalry with Mazada's Samurai New Japan group, Minoru Suzuki, and Voodoo Murders.

At AJPW's "Fan Appreciation Day" show, The Mexico Amigos teamed with Ray Suzuki and defeated Ryuji Hijikata, Kikutaro, T28 and Ryuji Yamaguchi.
After the match, Ray Suzuki revealed himself as Minoru Suzuki and stated that starting next year he would throw his Amigos tights away and return to NOSAWA Rongai, then kidnapped him to start early training.
This led to Pepe and Miguel stating they would return to Mexico, but Kaz and Taka would return come the new year.
After one last "Viva Mexico", the Mexico Amigos disbanded.

On February 6, 2009, Hayashi defeated Naomichi Marufuji to win the World Junior Heavyweight Championship for a second time.
During Hayashi's 23-month reign, he successfully defended the title a record–breaking seventeen times.
He would lose the title to Minoru on January 2, 2011.

In June 2013, Hayashi announced his resignation from All Japan in the aftermath of Nobuo Shiraishi taking over as the president and Keiji Mutoh leaving the promotion.
Hayashi's final match for the promotion took place on June 30 and saw him and his longtime tag team partner Shuji Kondo, who was also leaving All Japan, unsuccessfully challenge Burning (Atsushi Aoki and Kotaro Suzuki) for the All Asia Tag Team Championship.
After returning to Japan, Hayashi eventually decided to join All Japan Pro Wrestling (AJPW) due to his friendship with Keiji Mutoh and established himself as one of their top stars, winning the World Junior Heavyweight Championship and both the World Tag Team Championship and the All Asia Tag Team Championship with Satoshi Kojima. In 2006, Hayashi won the AJPW Junior League tournament.
Now under the name Miguel Hayashi Jr., Hayashi, PEPE Michinoku, and El NOSAWA Mendoza formed a team during the AJPW Champion Carnival called Mexico Amigos. Nobutaka Araya joined the team after six-man Action between Mexico Amigos and Araya/Fuchi/Hirai at the Carnival's final show.
After multiple bouts against Minoru Suzuki, Nosawa offered Suzuki an invitation into Mexico Amigos, which he declined. This resulted in the group changing multiple assets. Their name was changed to Mexico Amigos Black, the previous worn Mexican Flag attire became Black and Gold attire, and Nobutaka Araya was kicked out of the group. The groups is currently in a heated rivalry with Mazada's Samurai New Japan group, Minoru Suzuki, and Voodoo Murders.
At AJPW's "Fan Appreciation Day" show, The Mexico Amigos teamed with Ray Suzuki and defeated Ryuji Hijikata, Kikutaro, T28 and Ryuji Yamaguchi. After the match, Ray Suzuki revealed himself as Minoru Suzuki and stated that starting next year he would throw his Amigos tights away and return to NOSAWA Rongai, then kidnapped him to start early training. This led to Pepe and Miguel stating they would return to Mexico, but Kaz and Taka would return come the new year. After one last "Viva Mexico", the Mexico Amigos disbanded.
On February 6, 2009, Hayashi defeated Naomichi Marufuji to win the World Junior Heavyweight Championship for a second time. During Hayashi's 23-month reign, he successfully defended the title a record–breaking seventeen times. He would lose the title to Minoru on January 2, 2011.
In June 2013, Hayashi announced his resignation from All Japan in the aftermath of Nobuo Shiraishi taking over as the president and Keiji Mutoh leaving the promotion. Hayashi's final match for the promotion took place on June 30 and saw him and his longtime tag team partner Shuji Kondo, who was also leaving All Japan, unsuccessfully challenge Burning (Atsushi Aoki and Kotaro Suzuki) for the All Asia Tag Team Championship.
Kaz Hayashi