The AntiSora is a character who can be found exclusively as a boss in Kingdom Hearts and Kingdom Hearts Final Mix.
When Sora encounters Riku on Captain Hook's ship, Riku reveals that he now has control over the Heartless. To prove it, he creates a Heartless replica of Sora before his eyes, and it throws them into the ship's brig. As Sora fights his way back to the ship's deck, he encounters many of these Shadow Soras, which only he can defeat.
Character is error.