When Sora and his friends encounter Riku on Captain Hook's ship, he revealed that he had control over the Heartless, and created Shadow Sora’s to prove it. Once Sora had fought his way to the Captain’s Cabin, Riku creates a more complete replica of Sora, AntiSora, who was also able to wield a keyblade. AntiSora is the antagonistic, Heartless copy of Sora, using the prefix “anti-“ in his name which means “against.”
Awesome cosplay! Really love how his eyes are glowing gold, a symbol of the Heartless! Thanks to Phoenix for sending this!