[2] As a result of his win, Kai earned his first shot at the World Junior Heavyweight Championship, but was defeated in the title match on August 31 by the defending champion, Ryuji Hijikata.
[8] On September 6, 2009, Kai returned to Mexico to work events held by the Alianza Universal de Lucha Libre (AULL) and International Wrestling Revolution Group (IWRG) promotions.
[10][11] On January 30, 2010, Kai made his American debut for Pro Wrestling Guerrilla (PWG) in Los Angeles, California as part of WrestleReunion 4.
[12][13] Back in All Japan, Kai received another shot at the World Junior Heavyweight Championship on March 21, 2010, but was again defeated by the defending champion, this time Kaz Hayashi.
[24] This led to a match on October 23, where Kai lost the World Junior Heavyweight Championship to Omega, ending his reign at two successful defenses and 126 days.
[25] Kai, however, ended his year on a high note, when he and Seiya Sanada won the 2011 World's Strongest Tag Determination League by defeating Masakatsu Funaki and Masayuki Kono in the finals on December 4.
[28] On June 1, Kai returned to the United States, teaming with The Great Muta to defeat Anthony Nese and Sami Callihan at a Pro Wrestling Syndicate (PWS) internet pay-per-view in Rahway, New Jersey.
[29] Kai's second World Junior Heavyweight Championship reign lasted just 77 days as he lost the title to Hiroshi Yamato in his first defense on August 12.
[31] On February 23, 2013, All Japan Pro Wrestling announced that Kai would be making his return to the ring and his debut as a heavyweight on March 17 against Seiya Sanada in Ryōgoku Kokugikan.
Though an MRI revealed no abnormalities in the bone or ligaments, Kai had suffered biceps damage, which would take three months to heal, sidelining him from in-ring action.
[46][47][48][49] While Kai was out with his injury, Nobuo Shiraishi took over as the new president of All Japan, leading to former owner Keiji Mutoh, as well as several wrestlers loyal to him, quitting the promotion.
[53][54][55] Kai returned from his injury during the promotion's inaugural event on September 8, when he defeated his surprise opponent Seiya Sanada in a singles match.
[81] On February 15, Kai ended his losing streak, when he first defeated Minoru Tanaka in a first round match and then Masakatsu Funaki in the finals to win the tournament and earn a shot at the TNA World Heavyweight Championship.
[90] On March 22, Kai teamed up with Masayuki Kono and René Duprée, two members of the villainous Desperado stable, to take on Soya, Kaz Hayashi and Shuji Kondo in a six-man tag team match, which ended with Kai scoring another pinfall win over Soya, however, only after he had first been hit with a steel chair by Kono.
[100][101][102] From July 21 to 30, Kai took part in Pro Wrestling Zero1's 2014 Fire Festival tournament, where he finished at the top of his round-robin block with a record of three wins, one draw and one loss, advancing to the knockout stage.
[120][121][122] After picking up a major win over Pro Wrestling Zero1 representative Masato Tanaka on February 13,[123] Kai announced he was now ready to challenge Keiji Mutoh for the Wrestle-1 Championship.
[140] On April 24, Kai took part in a Guts World event and used the hold to win a six-man tag team match, which also included Mr. Gannosuke.
[147][148] On July 3, Kai and Ken Ohka won the DDT Pro-Wrestling promotion's KO-D Tag Team Championship by defeating Daisuke Sasaki and Shuji Ishikawa.
[150] On August 28, Kai and Ohka lost the KO-D Tag Team Championship to Harashima and Yuko Miyamoto in their first defense at DDT's biggest event of the year, Ryōgoku Peter Pan 2016.
[153][154] On December 18, Kai and Yusaku Obata defeated Akebono and Shogun Okamoto in the finals to win Pro Wrestling Zero1's 2016 Furinkazan Tag Tournament.
[159] On February 3, Kai received a shot at Zero1's World Heavyweight Championship, but the match against defending champion Kohei Sato ended in a thirty-minute time limit draw.
[162] On March 2, Kai and Yusaku Obata unsuccessfully challenged Akebono and Shogun Okamoto for the NWA Intercontinental Tag Team Championship.
[169][170] Three days later, Kai and Obata were stripped of the NWA Intercontinental Tag Team Championship due to Zero1 being unable to book a title defense for the two because of scheduling conflicts.
[172] Kai made his debut for Dragon Gate in August 2018, teaming with former partner Hiroshi Yamato to defeated Kagetora and Yosuke Santa Maria.