Setting The universe of
Kingdom Hearts is a collection of various
levels, referred to as "worlds", through which the player must progress. Fourteen worlds are featured, out of which thirteen can be accessed; one, Disney Castle, is shown in cutscenes, and additional worlds are mentioned by various characters, but are inaccessible due to being destroyed by the
Heartless. Ten Disney worlds are based on fiction, primarily from the
Disney animated features canon, and the other four were created by Square specifically for the game. The graphics and characters of each world were designed to resemble the artwork and style of the Disney film they are based on. Each Disney world is inhabited by characters from the film: for instance,
Hercules and
Philoctetes appear in Olympus Coliseum, and
Aladdin,
Jasmine, and
Jafar in Agrabah. Each world is disconnected from the others and exists separately, and with few exceptions, most characters in the world are unaware of other ones. Players travel from one world to another via the Gummi Ship. Traverse Town, which serves as a hub world and refuge for those whose worlds were destroyed; Hollow Bastion, home of several
Final Fantasy characters; and the End of the World, a large, dark world created from the remnants of various worlds consumed by the Heartless. The main characters, Sora, Donald, and Goofy, travel from world to world to seal the world's "Keyhole", which protects it from the Heartless and from destruction, while trying to minimize their interaction with characters of other worlds to maintain a balance of separation, which sometimes requires them to change their physical appearance to blend in with the world's inhabitants.
Characters The collaboration between Disney and Square resulted in a mixture of familiar Disney and Square characters, as well as several new characters created and designed by Tetsuya Nomura. The primary protagonist of the game is
Sora, a 14-year-old boy chosen to wield the
Keyblade—a weapon which is a cross between a key and a sword—to battle darkness. The game also features two friends from his home world,
Riku and
Kairi. For most of the game, Sora is joined by
Donald Duck and
Goofy, who are a court wizard and captain of Disney Castle's royal guard respectively, and were sent to find the Keyblade wielder, joining forces with Sora to search for their King,
Mickey Mouse, while Sora searches for Kairi and Riku. The primary antagonist is
Ansem, who seeks power and knowledge by using the Heartless, while
Maleficent, from the 1959 film
Sleeping Beauty, leads a group of
Disney villains that seeks to use the Heartless for their own gain. As a game meant to explore the fictional universes of various Disney films, over one hundred Disney characters are featured in various capacities. While many serve as major characters in the story, others appear in cameo roles, such as the
One Hundred and One Dalmatians being part of a side-quest where the player receives rewards for collecting and returning them to Pongo and Perdita. Most worlds also feature a Disney villain whom the player must defeat. Square also incorporated several characters from the
Final Fantasy series into the game, though altered to fit the game's story. Destiny Islands features younger versions of
Tidus and
Wakka from
Final Fantasy X (2001) and
Selphie Tilmitt from
Final Fantasy VIII (1999). In Traverse Town, the player encounters
Squall Leonhart, also known as Leon, from
Final Fantasy VIII, as well as
Aerith Gainsborough,
Cid Highwind, and
Yuffie Kisaragi from
Final Fantasy VII (1997).
Cloud Strife and
Sephiroth from
Final Fantasy VII make appearances in Olympus Coliseum, where the player can fight them in tournaments. The game also uses other
Final Fantasy icons, such as the
Moogles, who mediate item synthesis.
Story Sora, Riku, and Kairi build a raft with the intent to leave their home world of Destiny Islands to explore new worlds. On the night before the planned voyage, the Heartless attack the islands and Riku and Kairi disappear. Before the Heartless consume the islands, Sora mysteriously obtains the Keyblade, a weapon effective against the Heartless. Meanwhile, King Mickey has left his own world to deal with the increasing number of Heartless, leaving instructions for Donald and Goofy to find the "key" that will protect the worlds from encroaching darkness. Donald and Goofy use the Gummi Ship to travel to Traverse Town, where they find Sora after he wound up there following the destruction of his world. The three decide to travel together – Donald and Goofy to find Mickey, and Sora to find Kairi and Riku – traveling to various worlds and sealing their "Keyholes" to prevent their "heart" from being consumed by the Heartless. Meanwhile, a group of Disney villains led by Maleficent seek out the seven
Princesses of Heart to unlock the final keyhole that leads to Kingdom Hearts, a repository of knowledge and power and the source of all hearts. Maleficent also finds Riku and recruits him into her services, manipulating him into believing that Sora abandoned him. Sora and his friends eventually arrive at Hollow Bastion, Maleficent's headquarters, where Riku takes the Keyblade from Sora and reveals himself to be its intended wielder, with Sora only receiving it in his absence; Donald and Goofy reluctantly leave Sora as per their orders. Sora later challenges Riku, stating that his heart derives strength from his friends, inspiring Donald and Goofy to return to him and allowing him to regain control of the Keyblade. After the three defeat Maleficent, Sora finds Kairi's comatose body and confronts Riku, who has been possessed by Ansem, a figure who manipulated Maleficent to open the way to Kingdom Hearts. Ansem reveals Kairi as the seventh Princess of Heart, her heart having transferred into Sora's body when the Destiny Islands were destroyed. After defeating the possessed Riku, Sora impales himself with Ansem's Keyblade, which is designed to unlock hearts, and releases both his and Kairi's hearts. Kairi's heart returns to her body, in turn completing the final Keyhole, while Sora becomes a Heartless. However, Kairi recognizes Sora's Heartless, and the light in her heart restores him to human form. Sora and his group venture to the End of the World, the remnants of the worlds destroyed by the Heartless, to confront Ansem as he reaches the door to Kingdom Hearts. Believing a wellspring of darkness lies within the door, Ansem calls upon it to aid him after a battle with Sora. However, the door opens to reveal light, which destroys Ansem. Also beyond the door are Mickey and Riku, who help Sora and his friends close the door before Sora and Mickey lock it with their Keyblades from both sides. The worlds lost to the Heartless reconstruct themselves; as the Destiny Islands reform, Kairi returns there while Sora is forced to part with her. Sora, Donald, and Goofy resolve to find Riku and Mickey. ==Development==