Former five division world champion Floyd Mayweather Jr. and Japanese kickboxer Tenshin Nasukawa, first announced last month, was abruptly scrapped by Mayweather over a "misunderstanding", according to the CEO of mixed martial arts promotor RIZIN.
But the three round exhibition is fully back on for New Year's Eve.
The Mayweather camp had been confused if the fight would be official or not, according to Sakakibara.
Mayweather confirmed the fight would go ahead in Saitama, north of Tokyo, but would be an exhibition.
The unbeaten 41-year-old made it clear at a recent media gathering that their contest would involve no kicking, saying: "It's going to be a little boxing exhibition."
Sakakibara confirmed the fight would be an orthodox boxing style without kicking, which will be a disadvantage for Nasukawa.
Sakakibara also said the contracts remained unchanged as the highest paid for such an exhibition, but did not reveal the amounts.
The promoter compared the event to the first Rocky film, as well as to the 1976 match between Muhammad Ali and Japanese wrestler Antonio Inoki.
Mayweather, who beat UFC fighter Conor McGregor via a 10th-round technical knockout in a boxing match at the T-Mobile Arena in Las Vegas in August 2017, told fans to expect a lot of "entertainment" in the bout.
"The fight is very close and I'm training hard every day to face Mayweather and leave a mark. This is a great opportunity and we're happy to take it. I'm going to put everything out there and show my strengths. I think that I'm the faster fighter. I'm going to use my weapons against him," Nasukawa said.
"There's never been a Japanese fighter to face Floyd Mayweather in the ring. As an athlete, this is something that's a great honor and a challenging task. I'd like to make a big impression.
"I want to get the whole fight community, the whole country of Japan and the entire world involved in this fight. I'm going to go in there believing in myself and ready to prove myself."