Destiny Islands is a world in Stygian Solace.
The children play Island War on the play island. The game culminates as Tidus and Wakka try to knock Riku into the water from his hiding place under the broken bridge. Riku and Sora, however, manage to win the game.
Later, Riku collects raft materials and discusses romance and other worlds with Sora and Kairi. As they leave to go home, Riku tosses Sora a paopu fruit, but Sora tosses it away.
Riku spends the night at Sora's house instead of his own. Sora, unbeknownst to Riku, has gone back to retrieve Riku's paopu.
The next day, on the play island, Riku defeats Tidus, Selphie and Wakka in a play fight. He and Sora race, with the reward to be sharing a paopu with Kairi, and Sora wins. They race again and end up falling into the water. Sora goes to get a towel, returns with a paopu, and confesses his love to Riku.
After being interrupted by Tidus, Riku and Sora discuss their relationship with each other and with Kairi. Riku goes home to leave a note for his parents not to expect him home, and comes back to the play island, where he meets Sora. The two go to dinner at Sora's house.
Back at the play island, Riku overhears Kairi kidding about leaving him behind, but is not amused. Later, Kairi walks in on Riku and Sora alone, finding out about their relationship. Sora reassures her that she can still come on the raft trip.
That night, a horrible storm hits the Destiny Islands. Riku goes to check on the raft, but is swallowed by the darkness and is told by a mysterious voice to summon "the key". In the secret place, he encounters Kairi just before the Heartless appear. A mysterious man appears and sends Riku to the paopu island, and the darkness envelops Kairi.
Sora meets Riku on the paopu island and takes Riku's hand just as the two are swallowed by the darkness.