From what one source has reported the bout took some time to organise as both teams looked elsewhere for a bout and spoke to other fighters for an upcoming bout.
It seems that Corrales was in serious talks to face WBO champion Vasyl Lomachenko, with the intent being to grow his name Stateside. As we know however Lomachenko has instead chosen to face the more well known Nicholas Walters, in what should be a fight that every fan gets behind and should enjoy in November. Uchiyama was himself said to be in talks to face Jason Sosa, with Sosa instead taking a fight with Stephen Smith and the winner of that being tied up with a future bout with Javier Fortuna Incidentally Sosa's team had apparently looked into a bout with Sosa themselves before Sosa went a different direction.
Due to both teams wanting the bout, and other avenues failing to come to fruition the two teams agreed a deal, a deal that had looked likely for the last few weeks.
Although agreed in principle the bout hasn't been announced, though it's expected to be made official in October. It still seems like some T's need crossing and i's need dotting but everything is said to have been agreed by both teams and we will see the two men face off on New Year's Eve, on TV Tokyo in the Tokyo, or wider Kanto region.
Yes the Super Featherweight division is going to be fun over the coming months...and that's without mentioning the WBC situation...