Sora, Riku and Kairi dream of discovering worlds and solving the mystery to Kairi's appearance on Destiny Island. The night before they embark on their journey, Sora awakens to the destruction of his home, his world. Riku and Kairi disapear in the mist of all the confusion and Sora miraculously appears in Traverse Town, a place where all survivors of the Heartless attacks.

In search of his missing friends, Sora meets Donald and Goofy, who in turn are looking for their king, Mickey. He disappeared after he noticed that the stars were disappearing one by one in the sky. He told them to look for the Key Wielder, a hero that can right the darkness that is over taking the world...

Sora shows then the Key he holds as a sword and from there, the adventure begins.