Here is a list of Yamaguchi's best fights. For a list of Yamaguchi's losses, refer to "Mamoru Yamaguchi Losses".
On December 17, 2000 Mamoru Yamaguchi fought Jin Akimoto in a featherweight title fight for Akimoto's Shooto title. Yamaguchi was 23 years old and with a record of 6-0-1 (3), and Akimoto was 29 years old and with a record of 7-4-2 (3). Yamaguchi won the fight via 3-round unanimous decision and is crowned the new featherweight world champion.
On October 4, 2014 Mamoru Yamaguchi faced off against Yosuke Saruta in a light-flyweight bout at age 37. He was coming in with a record of 27-9-4 (15), and Saruta was 27 years old and with a record of 9-4-2 (3). Yamaguchi stopped Yosuke Saruta via TKO.
On August 27, 2000 Mamoru Yamaguchi faced off against Yoshinobu Ota at age 23. He was coming in with a record of 5-0-1 (3), and Ota was 27 years old and with a record of 3-1 (0). Yamaguchi stopped Yoshinobu Ota via KO.
On September 5, 1999 Mamoru Yamaguchi faced off against Jin Akimoto at age 22. He was coming in with a record of 2-0 (0), and Akimoto was 28 years old and with a record of 5-3-2 (2). Yamaguchi won the fight via 2-round majority decision.
On April 14, 2002 Mamoru Yamaguchi faced off against Hiroaki Yoshioka in a flyweight bout at age 24. He was coming in with a record of 8-1-1 (4), and Yoshioka was 28 years old and with a record of 4-3-2 (2). Yamaguchi won the fight via 3-round unanimous decision.
On April 24, 2016 Mamoru Yamaguchi faced off against Senzo Ikeda in a light-flyweight bout at age 38. He was coming in with a record of 29-10-5 (15). Yamaguchi won the fight via 3-round split decision.
On December 17, 2005 Mamoru Yamaguchi faced off against Daiji Takahashi in a bantamweight bout at age 28. He was coming in with a record of 15-2-2 (7), and Takahashi was 28 years old and with a record of 6-7-2 (1). Yamaguchi won the fight via 3-round unanimous decision.
On October 2, 2016 Mamoru Yamaguchi faced off against Luis Nogueira in a light-flyweight bout at age 39. He was coming in with a record of 30-10-5 (15), and Nogueira was 31 years old and with a record of 21-4-1 (11). Yamaguchi won the fight via 3-round split decision.
On October 30, 2009 Mamoru Yamaguchi faced off against Jesse Taitano in a bantamweight bout at age 32. He was coming in with a record of 21-5-3 (10). Yamaguchi stopped Jesse Taitano via TKO.
On August 9, 2015 Mamoru Yamaguchi faced off against Yusuke Kitago in a light-flyweight bout at age 38. He was coming in with a record of 28-9-5 (15). Yamaguchi won the fight via 3-round split decision.