Rizin FF 13 takes place on December 31st at Saitama Super Arena.
Floyd Mayweather is reportedly set to make his MMA debut against an undefeated fighter. "But we told the people anything is possible, so now we're here and we want to make sure that we give the people in Tokyo what they want to see: blood, sweat and tears".
Mayweather had teased a move into mixed martial arts for some time, both as a rematch with McGregor and as a potential superfight against undefeated UFC lightweight champion Khabib Nurmagomedov.
Former five-weight world champion Mayweather beat UFC's Conor McGregor in a boxing match in August 2017 to extend his flawless record to 50 wins.
"As far as the weight class and the rules, we will talk about that and will get that situated within the next couple of weeks", Mayweather added.
Mayweather will turn 42 in February, but he said he's looking forward to working with Rizin FF and fighting a unsafe opponent in 20-year-old Nasukawa, who is undefeated in kickboxing competition and most recently defeated Kyoji Horiguchi.
"I want to continue coming over here and bringing other fighters so my company can continue to grow and RIZIN can continue to grow".
Speaking at a news conference in Tokyo on Monday, Mayweather said the decision to fight in Japan was about expanding his global profile.
"I just want to entertain. But it will be a great fight that everybody will be so excited to see".
Rizin chairman Nobuyuki Sakakibara, who used to run the now-defunct Pride Fighting Championships promotional company, said they were still working out some of the details. "I'm so happy that Mr. Nasukawa accepted this offer in a flash".
Via MMA fighting he said: "I think my shortest answer to that is the fact that now we are aligned to achieve something together, and that is hitting a new challenge, taking a step forward to whatever wonderful thing that we can create together".
'I can wrestle, I can wrestle a little bit.
"Nobody has defeated my opponent in the past and I'd like to be the man to make history".
'I wanted to do something different.
Information from ESPN's Ariel Helwani was used in this report.