Update the text to be less complicated:
Sora, Riku, and Kairi build a raft with the intent to leave the Destiny Islands and explore new worlds.
Sora and his best friends, Riku and Kairi, plan on leaving their homes on Destiny Islands to explore their world, but their plans are interrupted when their world is attacked by the Heartless; monsters who steal people's hearts. <SEP> Their world is destroyed, and Sora, Riku and Kairi end up on different worlds.