
The pair share many common opponents but notably, Strikeforce lightweight champion Gilbert Melendez.
The hopes of Japan were upon Aoki's shoulders going into Strikeforce: Nashville in April but he failed to offer a challenge to Melendez and easily lost a five round decision.
Kawajiri fared much better however on New Year's Eve 2006 against Melendez, also losing a decision but only by the narrowest of margins with many observers giving the fight to "Crusher".