Kingdom Hearts II Story
After Roxas disappears, Sora wakes up and becomes the new player character. Donald and Goofy also wake up, and the three of them continue their mission to find Riku. As they search for him, they meet the rest of the members of Organization XIII and learn that they are beings called Nobodies. When a Heartless steals someone's heart, that person also becomes a Heartless, but if their heart is strong, their body becomes a Nobody. Nobodies have no emotions, but want to have hearts again. Xemnas, the leader of Organization XIII, is trying to summon Kingdom Hearts, which he claims will enable the Nobodies to get their hearts back. To summon Kingdom Hearts, Heartless must be killed with a Keyblade, which will release the hearts they hold and let them return to Kingdom Hearts. This is the reason the Organization wanted Sora to join them.