Amateur career Tahara competed in the Copa Palestra East Japan Shooto Grappling Open Tournament, held on September 28, 2003, and competed in the flyweight division. He finished as the second best of five participants, losing to Koji Murofushi in the finals. On July 14, 2004, Tahara took part in the 4th East Japan Amateur Shooto Tournament, competing in the flyweight (114 lbs) division. He finished as the third best of eleven competitors. This allowed him to compete in the 11th All Japan Amateur Shooto Championship, which was held on September 20, 2004. He finished as the third best. Tahara participated in the 5th East Japan Amateur Shooto Championship as well, which was held on August 14, 2005, and once again finished as third best. His third place allowed him to compete in the 12th iteration of the All Japan Amateur Shooto Championship, where he finished as the third best, same as the previous year, losing to
Shinya Murofushi in the semi-finals. Following this loss, Tahara decided to become a professional mixed martial artist.
Shooto Early professional career Tahara made his professional debut against Takeshi Yamada, under the ring name of Tahara Simpe, at
Shooto: 3/3 in Kitazawa Town Hall on March 3, 2006. He lost the fight by unanimous decision. On February 18, 2007, Tahara participated in the 4th East Japan Shooto Grappling Open bantamweight tournament. He finished as the runner-up, losing to
Hiroyuki Abe by points in the final. Tahara was scheduled to face
Kenichi Sawada, in his second professional appearance, at
Shooto: 11/30 in Kitazawa Town Hall on November 30, 2006. He won the fight by a second-round technical knockout. This victory earned him the place in the Shooto Rookie of the Year flyweight tournament. Before this tournament, he changed his ring name from Tahara Simpe to his birth name Noboru Tahara. Tahara was scheduled to face
Hiroyuki Abe in the opening round of the tournament at
Shooto 2007: 6/30 in Kitazawa Town Hall on June 30, 2007. He won the fight by a second-round technical knockout. Abe's camp later filed a complaint claiming the cut Abe's eye, which cause the fight to be stopped, was caused by a headbutt. Shooto agreed and changed the fight result from a technical knockout victory to a technical decision loss for Tahara.
First winning streak Tahara was scheduled to face
Junji Ito at
Shooto: Shooting Disco 3: Everybody Fight Now on October 20, 2007. He earned his second professional victory by unanimous decision. Tahara was scheduled to face Takehiro Ishii at
Shooto: Shooting Disco 4: Born in the Fighting on February 23, 2008. He won the fight by unanimous decision. Tahara was scheduled to face Katsuya Murofushi at
Shooto: Shooto Tradition 1 on May 3, 2008. He won the fight by a second-round technical knockout, due to a cut. Tahara was scheduled to face Atsushi Takeuchi at
Shooto: Shooting Disco 5: Earth, Wind and Fighter on June 21, 2008. He won the fight by a second-round submission, forcing Takeuchi to tap to an armbar at the 3:26 minute mark. Following this four-fight winning streak, Tahara was scheduled to face the streaking
Rambaa Somdet at
Shooto: Shooto Tradition 3 on September 28, 2008. Tahara was unable to land takedowns, excepting the solitary successful takedown in the second round, and lost the fight by unanimous decision. As Somdet as deducted a point in the first round, he won the fight by scores of 29-27, 29-26 and 29-27.
Flyweight title run Tahara was scheduled to face Takehiro Harusaki at
Shooto: Kitazawa Shooto 2009 Vol. 1 on March 20, 2009. The fight was ruled a split draw, with scores of 30-29, 28-30 and 29-29. Tahara was scheduled to face
Shinya Murofushi at
Shooto: Shooting Disco 9: Superman on June 6, 2009. He won the fight by a third-round technical knockout, finishing Murofushi through ground-and-pound. Tahara was scheduled to face Jesse Taitano in the main event of
Shooto: Gig Saitama 1 on August 9, 2009, in a 119 lbs catchweight bout. He won the fight by unanimous decision. Tahara was rewarded for his three-fight undefeated streak with a rematch with
Rambaa Somdet for the vacant
Shooto Flyweight Championship at
Shooto: Revolutionary Exchanges 3 on November 23, 2009. He lost the fight by unanimous decision, with scores of 30-27, 30-26 and 30-26. Tahara rebounded from this loss with a second-round technical knockout of
Junji Ikoma at
Shooto: Border: Season 2: Vibration on March 28, 2010.
Pancrase Early Pancrase career Tahara made his
Pancrase debut against Toshimichi Akagi at
Pancrase: Passion Tour 6 on July 4, 2010. He won the fight by majority decision. Tahara was scheduled to fight
Mitsuhisa Sunabe in a light flyweight title eliminator match at
Pancrase: Passion Tour 8 on September 5, 2010. Sunabe won the fight by a third-round stoppage, knocking Tahara out with a slam. Seven months later, on April 29, 2011, Tahara lost to Yuki Shojo at
Shooto: Shooto Tradition 2011 by unanimous decision. It was the first time his professional career, that Tahara lost back-to-back fights.
Pancrase light flyweight title run Tahara was scheduled to face Akinobu Watanabe at Shooto - Gig Tokyo 11 on August 25, 2012, and won the fight by majority decision. Tahara was next scheduled to face Takuya Eizumi at Pancrase - 245 on February 3, 2013. Tahara was scheduled to rematch
Hiroyuki Abe at Pancrase - 248 on June 30, 2013, six years after their first meeting. Tahara was more successful in the rematch, winning the fight by a 40-second knockout. Pancrase rewarded Tahara for his three fight winning streak with the opportunity to challenge the reigning
light flyweight champion
Mitsuhisa Sunabe at
Pancrase 252 - 20th Anniversary on September 29, 2013. Sunabe won the fight by unanimous decision, with scores of 30-29, 30-28 and 30-29. ==Mixed martial arts record==