Dubbed 'Iron Mike' by one time training partner BJ Penn, Hilo native Mike Aina is probably best known for his punching power, and for his fight in Elite XC against future Strikeforce welterweight champion Nick Diaz. Aina established a record of 9-5-1 before welcoming Diaz to the promotion, fighting fighters such as Roger Huerta. He spent a good majority of his career fighting for Hawaii's Rumble on the Rock promotion.

The fight against Diaz would be the first since Diaz shocked the world at Pride 33 when he submitted Takanori Gomi with a gogoplata, and was also Diaz's debut for the promotion. Despite being a massive underdog, Aina showed his confidence in his striking, and even stunned Diaz in the second round with a right hand. The commentating team of Mauro Ranallo, Stephen Quadros, and Bill Goldberg all believed that Aina may have won the bout. Aina fought off submission attempts in rounds two and three, and had success on the feet. Despite his valiant efforts, Aina dropped a split decision.

Aina would win two more fights, and would fight in the main event of the first ever Strikeforce: Challengers show against Billy Evangelista. The then undefeated Evangelista would land what originally appeared to be an illegal knee to Aina's head, and the fight would be stopped. Aina was awarded the victory, as Evangelista was disqualified. Later, the bout would be changed to a no contest, after video showed the knee hit Mike's shoulder, not his head.

'Iron' Mike's last fight was in 2010 in Hawaii, where he won a unanimous decision over local fighter Dominic Ahnee. He has not been in action since.