Before, it was just a matter of light and darkness.
Then it became one of existence versus nonexistence.
Now, it has evolved into something much greater, which encompasses all of these things.
A new organization has appeared, and they are after time. When you lose your heart, a Heartless is born from the body that lacks a heart, and a Nobody is born from the severance of body from heart. When your Heartless and Nobody are both destroyed, you have “lost your time” and become a Minute, a mindless creature whose sole purpose is to kill for time so they may survive. The most powerful Minutes took on a humanoid form and formed an alliance, called the Second Hands of Time.
Utilizing their time powers, they have salvaged the Organization XIII to ally themselves with; they believe that using the power of Kingdom Hearts combined with their time magic will succeed in regaining their original selves. The moment that they combined their powers to create a new dimension in which to reside, a shockwave of darkness spread across the universe, overwhelming the worlds with not just Minutes, but also Heartless and Nobodies.
King Mickey quickly ran to the Reception Chamber to speak with Goofy and Donald, his most loyal and heroic subjects. He instructed them to go find Sora and then report back to him so they can form a plan. The two just looked at each other, looked back at the King, and asked,”Who’s Sora?”