Floyd Mayweather will be laughing all the way to the bank after New Year's Eve fight in Japan

Legendary boxer Floyd Mayweather is coming out of retirement yet again, and this time, he’s fighting a 20-year-old who competes at 121 pounds and was less than 2 months old when Mayweather won his first professional world championship.

Mayweather will face highly regarded kickboxer Tenshin Nasukawa at Rizin 14 on New Year’s Eve in Tokyo. Rules for the bout and the weight class will be determined later, Mayweather said at a news conference Monday in Tokyo.

Of course, the one detail that undoubtedly has been finalized is the financial aspect, or Mayweather wouldn’t have shown up. Bank on this: Mayweather is going to be paid, and handsomely. Mayweather’s “The Money Team,” will partner with Rizin, and he said he plans to do business with Rizin in Tokyo in the future.

No one said how much Mayweather will make, but you can bet he wouldn’t have taken the bout had he not been guaranteed a nine-figure paycheck.

Several times during the news conference, Mayweather referred to creating excitement, and nothing excites him more than making huge amounts of money.

It’s an amazing end-of-career run for Mayweather, who is coming off a 10th-round stoppage of former UFC champion Conor McGregor in a 2017 boxing match that earned him his second nine-figure payday. Assuming Mayweather “only” makes $100 million for whatever the match is with Nasukawa, he’ll have earned more than $500 million just since 2015 alone.

Mayweather, who will be 42 on Feb. 24, downplayed the financial aspects, though.

“As far as the weight class and the rules, we’ll talk about that and we’ll get that situated within the next couple of weeks,” Mayweather said. “As far as they said money is the motivation, well, we all know that I had a great career. I was very truly blessed to be in the sport a long time and to make over a billion dollars in the sport and to make smart investments.”

Though he said the rules would be determined later, he seemed to hint it may be something out of the ordinary. Japan has famously had events in which fighters from different disciplines competed with each other.

The most famous was the 1976 match between legendary heavyweight champion Muhammad Ali and professional wrestling superstar Antonio Inoki.

Listening to Mayweather, one got the sense this fight could be something similar, though he was very short on specifics.

“This particular bout is a special bout as far as we’re giving the people something they’ve never seen before,” Mayweather said. “The world has never seen Mayweather compete live in Tokyo. Throughout the years, I’ve seen a lot of fans from Japan come to Las Vegas and come to the U.S., but me and my team said, ‘Let’s do something different.’”

Long-time Mayweather friend James McNair and Brent Johnson of One Entertainment reached out to Rizin’s Nobuyuki Sakakibara and, in Mayweather’s words, “came up with a concept.”

So we don’t know if it’s a real fight or something scripted like pro wrestling, or a variant in between. We do know that there is an extraordinary age, experience and weight difference.

Mayweather sloughed the weight difference off as if it were nothing, though he probably wouldn’t be too interested in fighting a light heavyweight boxer. But Nasukawa fights at a lighter weight than Mayweather was at when he turned pro in 1996.

“As far as the weight class, we’re not really worried about that,” he said. “When it’s all said and done, it’s all about me going out there and displaying my skills against another skillful fighter. We both want to go out there and display our skills and give the people excitement.”

It’s going to compete for viewers with a stacked UFC 232 card on Dec. 29, headlined by Jon Jones against Alexander Gustafsson and Cris Cyborg against Amanda Nunes.

But after all these years, the one thing we’ve learned is this: Don’t bet against Floyd Mayweather. If there is one thing he knows how to do better than anybody, it’s how to sell a fight.

Competition or not, Mayweather’s return, whatever it is, will captivate the sports world on New Year’s Eve.

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