I was looking at Best Buy and noticed it has a description that is not on Amazon or Gamestop. This gives some hints at the story and leads credence that we will play as Sora and Riku.

"Join your favorite Disney characters as they set off for adventure once again in the latest installment in the Kingdom Hearts legacy. Resume your place in this action RPG as you attempt to complete challenging missions with your favorite characters. Because of his firm but misguided belief that light and darkness must always remain in balance, the villainous Master Xehanort has sparked a flame that may turn into the all-out inferno of war against the "tyranny of light". Ask yourself — is equilibrium really worth the price of war?

It's up to you and your pals Sora, Donald and Goofy to undermine the catastrophic plot of Master Xehanort before it is too late. In an effort to do just that, these three set off on a journey to find the seven guardians of light, as well as the Key to Return Hearts. But these efforts alone may not be enough to halt war in its tracks. King Mickey and Riku must also search for previous Keyblade wielders in a final attempt to thwart Xehanort's nefarious plans. Gather your wits and buck up your courage — only you and your cast of Disney characters can stop this war."

And even more "Return to the , only this time, there's a war brewing — Master Xehanort is bent on stopping the "tyranny of light" from wrecking the balance between light and darkness Join Sora, Donald and Goofy as they set off to search for the seven guardians of light in a desperate effort to find the Key to Return Hearts and undermine Xehanort's plot Search alongside King Mickey and Riku as they seek to find the previous Keyblade wielders"

This gives us some of the first insights into the story and goals of the groups.

Link to the information:https://www.bestbuy.com/site/kingdom-hearts-iii-playstation-4/9497135.p?skuId=9497135