A professional competitor since 2005, Omigawa competed in the UFC, PRIDE, Cage Rage, World Victory Road, DREAM, DEEP, and Shooto.

He attended Tsuchiuranichidai High School with fellow mixed martial artists Hayato Sakurai and Kazuyuki Miyata.

[2] Omigawa made his professional mixed martial arts debut in 2005 against future UFC veteran Aaron Riley at PRIDE Bushido 7.

Omigawa then fought for the British Cage Rage organization against future two-time K-1 HERO'S Middleweight Champion Gesias Calvacante.

Though he lost his division debut against future WEC and UFC veteran Jung Chan-Sung, Omigawa made a resurgence when he entered the Sengoku Featherweight Grand Prix tournament promoted by World Victory Road.

After the tournament Omigawa continued to earn a spot as a world top five Featherweight, defeating the likes of Hatsu Hioki via a controversial split decision, Hiroyuki Takaya via TKO at Dynamite!!

[4] The decision was considered controversial, and despite the loss, UFC president Dana White stated on his Twitter account that both fighters would be paid a win bonus.

[5] Omigawa faced British fighter Jason Young on November 5, 2011 at UFC 138[6] and won the fight via unanimous decision.

After defeating Yuki Hiroshi Kimaya by unanimous decision in the quarter-finals, he then faced fellow mixed martial artist "Wicky" Akiyo Nishiura in the semis.