But a month before his fight with Strikeforce lightweight champion Gilbert Melendez, Aoki said that adding the Strikeforce lightweight belt would mean something particularly important to him, not just for personal pride, but for national pride.
"I believe that Japan is the No. 1 country in mixed martial arts, so I want to show that through this fight," Aoki said Wednesday, through a translator. "Being the champion of two promotions, Dream and Strikeforce, that has a special meaning to me, to show Japan as No. 1."
Aoki is regarded by most MMA fans as the second-best lightweight in the world, behind UFC lightweight champion B.J. Penn. Aoki says he has no plans to sign with the UFC, which means a fight with Penn wouldn't happen any time soon. But he does hope it happens eventually -- because he knows that until he dethrones Penn, he can't call himself the lightweight champion of MMA, no matter how many belts he owns.
"I'm getting stronger every day," Aoki said. "I'm not No. 1 at the moment but I'm getting stronger every day. In the future I may have a fight with B.J. Penn."
In addition to Penn, Aoki pronounced himself a big fan of the UFC's Kenny Florian, and he said he'll be watching with interest when Florian faces Takanori Gomi this month, although he declined to predict a winner in that bout.
Aoki said he's not concerned about the rules differences between Japan and the United States, which include fighting in a cage and forcing Aoki to wear shorts rather than the grappling pants he prefers. But he is concerned about Melendez, whom he described as one of the toughest opponents he's ever faced.
"I'm training in a cage so I'll be ready for that," Aoki said. "He's strong in every element. It's very difficult to find a weakness."
Aoki was in the United States on Wednesday for media interviews, but he's back to Japan on Thursday and won't return to the United States until about a week before he fights Melendez on April 17. That last week in the U.S. will be devoted mostly to staying loose and making sure he's on weight, which he says won't be a problem. He weighs about 165 pounds right now, 10 over the lightweight limit, and says he has no trouble making 155.
Until that weigh-in, American fans won't see Aoki, and that's how he likes it. For as excited as he is about the chance to fight for an American promotion's title belt, he says his first priority is to make a good showing for Dream, and for Japan.
"My schedule is dependent on Dream so Dream will decide when I fight again," Aoki said. "The United States is the biggest market so it's important for me to attract fans here and make a good impression in the U.S. market, but if I win the Strikeforce belt I am doing it for Dream and for Japan."