XIII機関
The game revolves around Roxas, who was first featured at the beginning of "Kingdom Hearts II". Roxas is the Nobody of Sora, the series' protagonist, born when Sora's body vanished as he briefly lost his heart and became a Heartless. Like Sora, Roxas has the power to wield the Keyblade, a weapon normally used for battling darkness. At the start of the game, Roxas joins Organization XIII, a group of powerful Nobodies who serve as the antagonists of "" and "Kingdom Hearts II". The other members of Organization XIII play a prominent role, particularly Axel, Roxas's best friend who debuted in "Chain of Memories". The game also introduces a new member: Xion, a girl resembling Kairi who, like Roxas, can wield the Keyblade.