The AntiSora is a near-perfect replica of Sora. It dresses in the same clothing as Sora, including his gloves, shorts, large shoes, hooded shirt, and even has the same necklace and hip chain. However, its clothing is colored entirely in shades of black and grey. Its skin is also black, as is its spiky hair. It carries a copy of the Kingdom Key, which is similarly dark-colored. It also has the glowing yellow eyes characteristic of Heartless.
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.
However, the replicas have no weapons and often vanish before he can even attack them. Once Sora reaches the Captain's Cabin, Riku creates a more complete replica of Sora, this one able to wield a shadowy Keyblade. After being defeated, it fades back into darkness.