Melvin Manhoef
Akiyama's mixed martial arts debut was in the "K-1 Premium 2004 Dynamite" event on December 31, 2004, where he defeated boxer Francois Botha by armbar submission in the first round. His first defeat was to Jerome LeBanner, who knocked him out with knees in his second fight at the HERO'S 1 event on March 26, 2005, although LeBanner is a heavyweight that came into the fight at 262 pounds (119 kg), while Akiyama came into the fight at 189.5 pounds (86 kg). He has notable wins against Tokimitsu Ishizawa, Taiei Kin, Kestutis Smirnovas and Melvin Manhoef. Akiyama defeated Melvin Manhoef at the Hero's light-heavyweight Grand Prix 2006 final round, and gained the champion belt.