About ten years or so pass, and Sora and Riku are teenagers now. They have no knowledge of the outside world, but for some reason, Riku believes they exist. With their friend, Kairi, they build a raft and plan to set out at sea. Before they leave, Sora is confronted by a mysterious hovering cloaked figure. This figure it supposed to be Xehanort, but that is explained in a much later game. He tells Sora that his world is about to be consumed by darkness.
The next day, it comes to pass. The island is consumed, and these strange creatures called Heartless show up. Unable to fight them, Sora searches for Riku, who tells him that the door has opened. Sora questions him, but they both disappear into darkness. Sora reappears with a keyblade in hand, now able to battle Heartless. He then searches for Kairi, who has lost her heart and disappears. Sora attempts to fight the darkness, but is blasted to another planet called Traverse Town.
There, he meets his long-suffering companions, Donald and Goofy. He also runs into familiar Final Fantasy characters Leon, Yuffie, and Aerith. He learns that he has to go to all the worlds to lock their hearts in order to protect them from the onslaught of the Heartless. He then goes from world to world, encountering Riku on the way. Riku, jealous of Sora’s keyblade, abandons him and sides with Maleficent, who resides at a planet called Hollow Bastion, formerly known as Radiant Garden.
Eventually, Sora finds out from Riku that Kairi’s heart has been lost. He chases Riku to Hollow Bastion, only to have the keyblade temporarily stolen from him. Sora gains it back and defeats Riku in a duel. Sora finds and defeats Maleficent, stopping her plan to create Kingdom Hearts from the hearts of seven princesses. Remember those Princesses of Heart? Since the events of Birth by Sleep, Maleficent has managed to kidnap and gather all of them, but is unable to complete Kingdom Hearts due to one missing heart: Kairi’s.
In search of more power, Riku allows the same mysterious hovering cloaked figure Sora saw on the island to possess him. Sora faces this possessed Riku and wins, only to find a lifeless Kairi. The possessed Riku (possessed by Xehanort) tells Sora that Kairi’s heart resides within Sora’s. Sora, taking the defeated Riku’s keyblade, unlocks his own heart, freeing Kairi’s heart and the other princesses’ hearts as well. In doing so, Sora disappears and ends up in the Realm of Darkness. All that is left of Sora is a Heartless.
Kairi calls out to Sora, causing him to come back from the Realm of Darkness. Together, they all return to Traverse Town, where Leon tells them that they need to return to Hollow Bastion to lock the heart of the world. Sora does and finds that he is being called to another world, which seems to be the source of the Heartless. With Donald and Goofy, he goes there and confronts the man who possessed Riku, now calling himself Ansem (but is really Xehanort). Riku is nowhere to be found.
Sora defeats Xehanort, who calls out to Kingdom Hearts for help. A ray of light blasts out of the doors of Kingdom Hearts, defeating this form of Xehanort. Sora runs up to the doors to close them, and finds Riku helping him from the other side. With a sad farewell, Sora closes Riku inside the Realm of Darkness and seals the Door to Darkness. Mickey Mouse seals it as well from within, sealing it on both sides. It disappears and the lost worlds begin to form again, including Destiny Islands. Sora happens to find Kairi there and tells her that he will find her once again. He disappears from view and Kairi is left alone on the newly reformed islands.
Chain of Memories
At the end of the first Kingdom Hearts, Sora, Donald and Goofy walk down a long green pasture. Enter Chain of Memories, where they finally come to the end of the path to a strange castle called Castle Oblivion. When they enter, they are greeted by a flamboyant bunch in dark hooded cloaks. They are with Organization XIII, a mysterious group of thirteen people in hooded cloaks whose motives are unknown.
The group warns Sora that the deeper he goes into the castle, the more he will lose his memories—Donald and Goofy as well. Sure enough, as they go deeper and deeper through different rooms and portals to worlds, they begin to lose their memories and suddenly, Sora begins to think his main goal is to save a girl named Namine. Donald and Goofy agree that they have never heard him speak of this girl, but Sora is filled with relentless determination.
Meanwhile, the small band of Organization XIII members sent to deal with Sora begin to plot against their main leader and want to use Sora for their own benefit. Marluxia becomes the coup leader and they begin to set their plan into motion. Axel, another member of the Organization, is sent to “aid” the group of members at Castle Oblivion, but he is really sent there to deal with the coup. One by one, Axel goes about eliminating each member.
While romping around the castle, Sora finds an exact replica of Riku, created by one of the members of the Organization. They lock swords and fight, but Replica Riku is defeated. It realizes its existence is meaningless and leaves the castle, seeking its own meaning.
Axel finds Namine and tells her that she has to rebuild Sora’s memories. Namine’s goal was to force Sora to like her through memory manipulation because she just wanted a friend. After a massive fight with Marluxia, Sora finds Namine, who tells him that his memories are corrupt and must now be rebuilt. She puts him, Donald and Goofy into a deep sleep while she rebuilds their memories.