In 2001, he began to lose his hair, and in November he turned heel, cast away his surfer gimmick, and he joined the original M2K as a replacement for Chocoflake K-ICHI.

The three of them would travel to Ring of Honor to take part in a match against Blood Generation's CIMA, Naruki Doi & Masato Yoshino, which would be given a rare five-star rating by famous wrestling columnist Dave Meltzer.

During the unit turmoil in the early parts of 2008, Horiguchi remained firmly on the heel side of Muscle Outlaw'z, and followed them to Real Hazard.

He acted as secretary to the Brave Gate belt commissioner Yoshito Sugamoto, which was actually the Brave Gate champion (and his fellow MO'z stablemate) Gamma himself, enforcing the outrageous rules randomly put in place by him that allowed Gamma to win title matches or retain his title if he lost the match.

On May 5, they won the Open the Twin Gate Championship from Susumu Yokosuka & Gamma in a Three-Way Match, which included fellow Real Hazard stablemates Kenichiro Arai & Yasushi Kanda.

On January 10, 2010, Horiguchi put out a blog where he stated that Real Hazard would win more matches via teamwork instead of illegal tactics and weapons play in 2010.

Tensions finally boiled over on February 10, after KAGETORA accidentally cost Sugawara a shot at becoming the next challenger for the Open the Dream Gate Title.

Genki remained a lone wolf up until the 27th, when Dragon Kid suggested him to CIMA and Gamma as a new member of the WARRIORS stable, and he was welcomed into the fold.

On May 13, 2010, Horiguchi, CIMA and Gamma defeated Don Fujii, Masaaki Mochizuki and Akebono to win the Open the Triangle Gate Championship.

On October 25, 2010, Horiguchi, CIMA and Gamma lost the Open the Triangle Gate Championship to Naoki Tanizaki, Yasushi Kanda and Takuya Sugawara.

[7] Horiguchi turned heel on January 14, 2011, along with the rest of WARRIORS, when they attacked Masato Yoshino and WORLD-1, and joined forces with Naruki Doi's unnamed group.

[8] On February 6, 2011, Horiguchi and his Blood WARRIORS stablemate Ryo Saito defeated Don Fujii and Masaaki Mochizuki to win the Open the Twin Gate Championship.

All the Members Set" 20th anniversary card, he teamed with Ryo Saito and Naoki Tanizaki against CIMA, Naruki Doi and Masato Yoshino at Korakuen Hall in Tokyo, Japan on August 21, 2005.