Mamoru Yamaguchi has 13 losses against 12 opponents on his MMA record. For a list of Yamaguchi's best fights, refer to "Best fights of Mamoru Yamaguchi".
On May 26, 2019 Mamoru Yamaguchi faced off against Toru Ogawa in a flyweight bout at age 41. He was coming in with a record of 31-13-5 (15). Yamaguchi lost the fight via 3-round unanimous decision.
On July 1, 2018 Mamoru Yamaguchi faced off against Yuya Wakamatsu in a flyweight bout at age 41. He was coming in with a record of 31-12-5 (15), and Wakamatsu was 23 years old and with a record of 9-2 (8). Yamaguchi lost the fight via 2nd-round TKO.
On August 20, 2017 Mamoru Yamaguchi met Senzo Ikeda in a flyweight (Pancrase Championship) title defense fight. Yamaguchi was 40 years old and with a record of 31-11-5 (15). Yamaguchi lost the fight via 5-round unanimous decision and lost the title.
On December 13, 2015 Mamoru Yamaguchi faced off against Yuki Yasunaga in a light-flyweight bout at age 38. He was coming in with a record of 28-10-5 (15). Yamaguchi lost the fight via 3-round split decision.
On February 23, 2014 Mamoru Yamaguchi faced off against Czar Sklavos in a light-flyweight bout at age 36. He was coming in with a record of 26-9-4 (14). Yamaguchi lost the fight via 1st-round submission.
On June 22, 2013 Mamoru Yamaguchi faced off against Mikihito Yamagami in a light-flyweight bout at age 36. He was coming in with a record of 26-8-3 (14), and Yamagami was 26 years old and with a record of 8-2 (3). Yamaguchi lost the fight via 3-round majority decision.
On December 24, 2012 Mamoru Yamaguchi faced off against Darrell Montague in a light-flyweight bout at age 35. He was coming in with a record of 26-7-3 (14), and Montague was 25 years old and with a record of 11-2 (9). Yamaguchi lost the fight via 3-round split decision.
On August 6, 2011 Mamoru Yamaguchi faced off against Jussier da Silva in a light-flyweight bout at age 34. He was coming in with a record of 26-6-3 (14). Yamaguchi lost the fight via 3-round unanimous decision.
On July 18, 2008 Mamoru Yamaguchi fought Shinichi Kojima in a bantamweight title fight for Kojima's Shooto title. Yamaguchi was 31 years old and with a record of 20-5-3 (9), and Kojima was 29 years old and with a record of 8-3-4 (4). Yamaguchi lost the fight via 3rd-round submission.
On September 22, 2007 Mamoru Yamaguchi faced off against Yasuhiro Urushitani in a bantamweight bout at age 30. He was coming in with a record of 18-4-3 (9). Yamaguchi lost the fight via 3-round unanimous decision.
On October 14, 2006 Mamoru Yamaguchi met Shinichi Kojima in a bantamweight (Shooto) title defense fight. Yamaguchi was 29 years old and with a record of 17-3-3 (9), and Kojima was 27 years old and with a record of 6-1-3 (3). Yamaguchi lost the fight via 1st-round choke-out and lost the title.
On September 16, 2002 Mamoru Yamaguchi faced off against Robson Moura in a flyweight bout at age 25. He was coming in with a record of 8-2-1 (4), and Moura was 24 years old and with a record of . Yamaguchi lost the fight via 3-round unanimous decision.
On November 25, 2001 Mamoru Yamaguchi met Masahiro Oishi in a featherweight (Shooto) title defense fight. Yamaguchi was 24 years old and with a record of 7-1-1 (4), and Oishi was 32 years old and with a record of 7-5-3 (4). Yamaguchi lost the fight via 1st-round submission and lost the title.
