The series starts with Kingdom Hearts, where a 14-year-old boy named Sora is separated from his friends Riku and Kairi when their home Destiny Islands is consumed in darkness. At that moment Sora obtained a weapon called the Keyblade that allows him to fight the Heartless, creatures that originate from the Realm of Darkness, before ending up in another world, Traverse Town, where he meets Donald Duck and Goofy, two emissaries from Disney Castle sent to find the Keyblade wielder under orders from their missing king, Mickey Mouse. As the three band together and travel to save various worlds from the Heartless while searching for their companions, encounter a group of Disney villains whose ability to control the Heartless was given to them by Maleficent, who enlists Riku's aid in seeking seven maidens called the Princesses of Heart whose power would open the way to Kingdom Hearts, the heart of all worlds. Though eventually defeating Maleficent and reunited with Kairi after sacrificing himself to restore her heart to her body, Sora learns that Maleficent was manipulated by a sentient Heartless who possesses Riku and claims himself as the Heartless researcher Ansem. Though Sora defeats Ansem, he is forced to trap Riku and Mickey in the Realm of Darkness after sealing the door and resolute to find them while Kairi remains at the Destiny Islands for their return.
In Kingdom Hearts: Chain of Memories, Sora's search for Riku and Mickey leads his group to Castle Oblivion, a fortress controlled by a mysterious group of non-existent "Nobodies" called Organization XIII, the castle's overseer Marluxia using the power of a girl named Naminé to alter the group's memories for his agenda. After Marluxia's defeat, the three are placed in a year-long sleep by Naminé to restore their original memories while losing their experience in Castle Oblivion. At the same time Sora ventured through Castle Oblivion, Riku ended up in the basement levels and ascends to the ground floor with Mickey's aid while dealing with a Replica of himself that fought Sora. Finding the comatose Sora while joining forces with the mysterious DiZ, Riku helps Naminé keep his friend safe until he is awoken. In Kingdom Hearts 358/2 Days, a snag in the plan over the year forces Riku to capture Roxas—Sora's Nobody and Organization XIII member that came into being when Sora briefly became a Heartless in the first game-after he was forced to defeat and absorb Xion, a Replica of Sora in Kairi's image.
In Kingdom Hearts II, after Roxas was integrated back into him, an awakened Sora and his friends resume their search for Riku and King Mickey, the latter's mentor Yen Sid re-familiarizing the trio with the Nobodies and Organization XIII's remaining members whom they deal alongside Maleficent and her right hand Pete. The three reunite with King Mickey and encounter Organization XIII's leader Xemnas, him and the Heartless Ansem revealed to the splintered halves of the real Ansem's apprentice Xehanort. The Organization's plan is also revealed: regaining their lost hearts by using Keyblade users to create an artificial Kingdom Hearts from slain Emblem Heartless. Axel, a rogue Organization member who is Roxas' friend and first encountered Sora in Castle Oblivion, abducts Kairi in an attempt to see Roxas. But Axel's action only give Saix, his former friend and Xemnas' enforcer, leverage to force Sora into finishing what Roxas and Xion began. Axel sacrifices himself to help Sora's group reach The World That Never Was (Organization XIII's headquarters) and, after defeating Xemnas's right hand Xigbar, reunite with Riku and Kairi. DiZ, revealed to be the real Ansem, attempts dissipating some of the artificial Kingdom Hearts before being engulfed in an explosion when his extraction device self-destructs and is sent to the Realm of Darkness. Sora and his friends then battle Xemnas. After Sora and Riku defeat Xemnas, they get trapped in the Realm of Darkness, but a letter from Kairi summons a gateway for them, and the two are reunited with their friends at their home. Sometime after his first adventure in Disney Castle, Sora discovered a portal at Disney Castle, and ventured through it to find a mysterious armour referred to as 'Lingering Will'. During their exchange, it mistook Sora for Xehanort, after which Sora fought the mysterious armour. Sora won the battle, and the Lingering Will merely knelt down after this, saying that he once felt the power Sora possessed.
Sometime later after the events of the game, Sora, Riku, and Kairi receive a letter from King Mickey. The letter, written by Mickey during the events of Kingdom Hearts Coded, describes the parts of their past that Naminé learned while restoring Sora's memory. As they read the letter, they learn of Xehanort's true identity as a Keyblade Master who sought the secrets of the Keyblade War which created their current reality and the fates that befall the apprentices of his friend Eraqus during the events of Kingdom Hearts Birth by Sleep: Terra having ended up possessed by Xehanort and made into the original being of Xehanort's Heartless and Xemnas were split from; Ventus sacrificing his heart by fighting his dark counterpart Vanitas while to prevent Xehanort from recreating the legendary χ-blade which allows the user to control Kingdom Hearts and hiding within four-year-old Sora's heart; and new Keyblade Master Aqua trapped within the Realm of Darkness while an amnesic Xehanort ended up Ansem's apprentice alongside his accomplice Braig (Xigbar's original self). King Mickey also discovers that the destruction of "Ansem" and Xemnas has led to Xehanort's restoration. To combat the new threat Xehanort poses, Sora and Riku take an exam to attain the Mark of Mastery that will allow them to become Keyblade Masters themselves.
During the test in Kingdom Hearts 3D: Dream Drop Distance, Sora and Riku enter the Realm of Sleep where they encounter a young version of Xehanort who can travel through time. The two Keyblade wielders also learn how Xehanort has long manipulated events since Birth by Sleep with Organization XIII's true purpose in providing thirteens vessels for him to inhabit and use against seven hearts of pure light in an ultimate battle to recreate the χ-blade. But Sora's interference forced Xehanort to retrieve his alternate selves, Marluxia, Larxene, Demyx, Luxord, Vantias, and Xion from across time in Replica bodies to form his ideal Organization XIII with Xigbar, Saix, and Vexen. Sora is narrowly saved from being Xehanort's final vessel with the aid of Lea (Axel's original self) and Riku learns about data that Ansem the Wise had implanted within Sora during his year-long sleep, which may be used to save those connected to Sora. At the end of the exam, Riku is declared a Keyblade Master; in Kingdom Hearts HD 2.8 Final Chapter Prologue, Sora embarks on another journey to regain his "Power of Waking" while Riku helps Mickey find Aqua, Yen Sid training Kairi and Lea so they can help in the final battle against Xehanort and keep him from the Princesses of Heart.
In Kingdom Hearts III, Sora regains his "Power of Waking" in his group's travels while Riku and Mickey retrace Aqua's steps to find her and Terra. Sora later discovers Eraqus's Keyblade on the beach and uses it to open a door to the Realm of Darkness, finding Aqua who has been consumed by darkness after Ansem was abducted by Xehanort's Heartless. Once Aqua is purified by Sora and Riku, she leads them to Castle Oblivion which she restores to its true form as the Land of Departure to revive Ventus despite Vanitas' interference. The group are joined by Kairi and Lea as they face Xehanort and his followers, with a Riku Replica completing the group, at the Keyblade Graveyard. After initially losing the fight, Sora once again uses the "Power of Waking" to restore the guardians and call upon the "Lingering Will" armour, to assist in the fight. Afterwards it is revealed that Saix and Vexen sabotaged the Organization's plan by restoring Roxas as Sora's group manage to defeat all of Xehanort's remaining selves while freeing Xion and Terra from his control. Xehanort kills Kairi to force Sora to manifest the χ-blade, revealing his true plan is to use the true Kingdom Hearts to wipe the slate on reality clean before finally being defeated. Xehanort departs with Eraqus's spirit into the light as Sora closes Kingdom Hearts. Sora also sacrifices himself by using the "Power of Waking" once more to revive Kairi. Sometime later, all the guardians, including their close friends and allies, celebrate victory at Destiny Islands. But Xigbar, revealed to be the current incarnation of the ancient Keyblade Master Luxu from the time of the Keyblade War, summons the Foretellers, his fellow Keyblade Masters, to the present for the next phase of his mission. A year later, all attempts to find a clue to Sora's current whereabouts have proven to be futile until Riku and Kairi, with the help of the Fairy Godmother, find clues that lead them to believe that Sora has been transported outside of their reality. Riku embarks on a search for him after opening a portal to another reality in the Final World. Elsewhere, Sora meets Yozora, a supposedly fictional character from a video game. During their exchange Yozora claims that he is tasked to "save Sora" and the world is transported into Shibuya. Sora is challenged to a fight by Yozora, whom he defeats. Yozora fades away as Sora returns to The Final World. Both Sora and Yozora wonder if their meeting was real, with neither character making sense of it.
