“Believing light and darkness must remain in balance, Master Xehanort seeks to spark war against the 'tyranny of light' to restore equilibrium.
In an effort to undermine Xehanort's plot, Sora, Donald, and Goofy search for seven guardians of light and the "Key to Return Hearts", while King Mickey and Riku search for previous Keyblade wielders.”
―Kingdom Hearts III press release
After setting off on his new journey in Kingdom Hearts 0.2 Birth by Sleep -A Fragmentary Passage-, Sora, Donald, and Goofy will attempt to search for seven guardians of light and the "Key to Return Hearts", as well as find a way to restore those in Organization XIII connected to Sora (Roxas, Xion, and Namine). Meanwhile, King Mickey and Riku search for other previous Keyblade wielders (Ventus, Terra, and Aqua), in an attempt to stop Master Xehanort's plan to "balance" the light and darkness, which will ultimately lead to the final showdown between Sora and Master Xehanort. Following the start of the game, Sora seeks out Hercules and through training regains his lost powers after what happened with Xehanort in Dream Drop Distance, completing his Mark of Mastery and becoming a Keyblade Master.
Kingdom Hearts III will serve as the final chapter of the "Dark Seeker" saga, with Nomura revealing that the plot of the game will pick up "immediately after the events of 0.2 Birth by Sleep -A Fragmentary Passage-." He also added that the plot will examine the seven lights and thirteen darknesses coming together for the final battle, but that everyone that is expected to fulfill these roles may not.
After Square Enix finished development of Kingdom Hearts II Final Mix+, Kingdom Hearts producer Tetsuya Nomura was approached by Disney who expressed interest in a sequel. In regard to a possible release of a Kingdom Hearts III, Nomura said "We have various ideas, but we're not at the point where we can say that." He added that due to the development of Final Fantasy XV (which at the time was Final Fantasy Versus XIII), "it's physically impossible at the present. I feel that it's not the right time to talk about the future of Kingdom Hearts." In response to questions as to the secret movie in Final Mix+, Nomura noted that it was of a "new series" in Kingdom Hearts rather than Kingdom Hearts III. When asked about Kingdom Hearts III, Nomura noted that fans and partners alike were interested in its release, and would work to "realize it" as soon as possible. In the Kingdom Hearts Birth by Sleep Ultimania guide book, Nomura announced three upcoming titles, one of which was Kingdom Hearts III. However, Final Fantasy XV was still his primary focus, preventing him from starting production on Kingdom Hearts III. He later noted that Kingdom Hearts III would not see a release until after 2012, due to his pressing on Final Fantasy XV, regardless of the 10th anniversary of the series occurring in that year. The Nintendo 3DS video game Kingdom Hearts 3D: Dream Drop Distance was announced to connect to Kingdom Hearts III, both in terms of gameplay system and story, similar to the connection between Kingdom Hearts: Chain of Memories and Kingdom Hearts II. It has been confirmed by Tetsuya Nomura that the game will conclude the "Xehanort Saga" but will not be the final game in the series.
On June 10, 2013, Kingdom Hearts III was announced with a teaser at Sony's E3 event, to release on the PlayStation 4. In a conference the day after, Square Enix confirmed that the game would also be released on the Xbox One. Unlike Kingdom Hearts and Kingdom Hearts II which were developed by Square Enix's Product Development Division 1 team, Kingdom Hearts III will be developed by Square Enix's 1st Production Department, who developed Birth by Sleep and Dream Drop Distance, and worked on the HD 1.5 Remix collection.
Directly after E3 2013, Tetsuya Nomura claimed that Kingdom Hearts III was announced "too early", based on where the game currently stands in development. He continued by saying, "Many fans were feeling impatient due to our continuous releases of spin-off titles, so we decided to announce it at the same time as Final Fantasy XV". In an interview with Famitsu in June 2013, Nomura discussed the updated visuals seen in the teaser trailer as well as the gameplay. On the visuals, he said that they tried to remember that these "Kingdom Hearts characters were originally paintbrush art from Disney productions, a texture that was one of our original aims, and that it was time to return to that. So [chief creative director Takeshi] Nozue went through a series of tests, and the results are the visuals that we refer to in the team as the Kingdom Shader. It may look like a pretty drastic change, but I see it as a rich evolution of everything we've shown you up to now."
Series producer Shinji Hashimoto stated in a September 2013 interview with IGN that as both Kingdom Hearts III and Final Fantasy XV are directed by Nomura, it is expected that there will be significant gap between the release of the two, "as [they] want each game to be perfect in terms of quality." Hashimoto also reiterated Nomura's statements about the game's announced at E3 2013, as "the company thought it was about time it addressed speculation about the long-awaited conclusion to the trilogy." In October 2013, Teruzane Utada, father of singer Hikaru Utada, stated on Twitter that Hikaru would once again be involved in the theme song for Kingdom Hearts III, as she did with Kingdom Hearts and Kingdom Hearts II. He later clarified, however, that it is still undecided on their involvement.
In an interview in the January 2014 issue of Game Informer, Nomura stated that the plot of the game will pick up "immediately after the events of Dream Drop Distance." He also added that the plot will examine the seven lights and thirteen darknesses coming together for the final battle, but that everyone that is expected to fulfill these roles may not. On the new gameplay seen in the D23 trailer, Nomura revealed that all keyblades transform, each in different ways, and confirmed that the attractions seen in the trailer, such as "Big Magic Mountain", are not tied to the keyblade abilities, but the enemy you are up against. Also in January, Sora's English voice actor, Haley Joel Osment, stated he had been in talk with the development team after the announcement and, assuming he would be back, expressed his belief that he would not begin voice recording until mid-2014 at the earliest.
In June 2014, a short teaser was released at the end of the E3 2014 trailer for Kingdom Hearts HD 2.5 ReMIX. Co-director Tai Yasue revealed that the sequence seen in the teaser was the opening scene for the game. He added that it was created by Nomura who had "a real clear picture of [what] the starting sequence" should be and that the text seen and heard was going to "be a real integral part of the story".
In September 2014, it was announced that Nomura would be leaving Final Fantasy XV development team as director, so he can focus his attention on other projects, including Kingdom Hearts III.
On October 6, 2014, it was announced that the game would be developed using Epic Games's Unreal Engine 4, instead of Square's Luminous Engine as previously announced.
In April 2015, Nomura stated there would be "news [and] new announcements" about the game in November 2015 at the Japan D23 expo.
In June 2015, Nomura revealed that development was on track and that as secret films were being considered. He also stated that the team has an internal release window they are trying to hit. On August 17, 2015 during the D23 Expo, Kingdom Hearts producer Shinji Hashimoto announced that a world based on Big Hero 6 will be featured in Kingdom Hearts III. In November 2015, new footage was shown at the Japan D23 expo, footage which was cut from the E3 2015 trailer for time.
A gameplay trailer was released during the Kingdom Hearts Orchestra World Tour in Los Angeles in mid-June 2017. At D23 2017, a world based on Toy Story was revealed and it was announced that the game would release in 2018.
On February 10, 2018, it was confirmed a world based on Monsters, Inc. will be included in the game.
Another new trailer was revealed revealing Utada Hikaru doing KH3's theme song, "Don't Think Twice".
Also, they talked about the development. The development is split into three parts. Part 1 is 90% complete, part 2 is 60 to 70% percent and part 3 haven't been given a percentage, but Tetusya Nomura is planning something for the final world.
On May 19, 2018, the Kingdom Hearts III Premiere Event began, allowing invited guests to play through a small demo of Kingdom Hearts III. A few weeks later on June 9, it was announced that the game would be pushed back to 2019.
At the E3 2018 Sony Press Conference, a new trailer was released, confirming a world based on Disney's Frozen.
The beach of Destiny Islands is then shown, with the Master's Defender Keyblade lying on the sand. Sora, now in his Kingdom Hearts II attire, approaches it and lifts it, looking at it curiously before shifting his gaze to the horizon. The trailer then cuts to black, revealing the new logo and the title of the game.
A gameplay video follows, revealing the HUD. An extra gauge, entitled "EX", appears around Sora's HP gauge. The MP gauge returns from Kingdom Hearts II. Gauges for Donald and Goofy appear to the right, rather than above like previous titles. The Command panel looks very similar to that of the previous console titles, albeit with a graphical revamp.
Sora begins running through Twilight Town, wielding the Kingdom Key. He is chased by a swarm of Shadows (later revealed to be a Demon Tide) and flees, dodging the swarm by jumping off the sides of buildings in a way similar to his Flowmotion abilities from Dream Drop Distance. After riding the swarm in a manner similar to Vanitas riding the keyblades in Birth by Sleep, Sora turns around and leaps to confront the swarm head on as the trailer cuts to black, revealing the game to be in development.
D23 Expo Japan 2013 Trailer
The trailer begins with Sora, Donald, and Goofy running into a group of Heartless in Twilight Town's Tram Common, consisting of Shadows and Large Bodies. Sora casts Fire as Donald and Goofy begin to aid him. Sora then commences to enter "Two Shoot Blaster" mode, a new battle technique that allows Sora to turn his Keyblade into twin pistols. Afterwards, the video fades to Sora using a "Pirate Ship" summon, lit up and swinging dealing damage to the Heartless below, finally ending with a massive barrage of circling the boat around.
Gameplay fades into another scene where Sora, Donald, and Goofy are on a "Big Magic Mountain" train ride going around the Rock Titan, the camera closes in on Sora then out as Sora attacks the Titan a couple of times before jumping on top of the Titan's hand getting back into his seat. The camera closes in on Donald now then back out as Sora attacks the Titan yet again. Sora leads the train upwards into the sky, high above the Titan, turns around facing the Titan and sends the train ride right into the Titan. As the group falls in the sky, the screen then fades to black and reveals that the game is in development.
On June 5, 2014, Square Enix released the E3 2014 trailer for Kingdom Hearts HD 2.5 ReMIX. Towards the end of the E3 2014 trailer, there is a teaser for Kingdom Hearts III. The 30-second teaser begins with several scenes from Kingdom Hearts 3D: Dream Drop Distance along with the line "The next act opens―" and then the line "KINGDOM HEARTS III" appears. The remainder of the teaser features two unidentified people, later revealed at E3 2015 to be Xehanort and Eraqus in their youth, who are talking to each other. The screen remains black, with sketches of their faces in white, though their faces are too zoomed-in to identify.
Xehanort: Have you heard of the ancient Keyblade War? Many years ago, Keyblade wielders fought a war over the ownership of light.
Eraqus: Yep, the Master loves telling that story.
Xehanort: Then I take it you have also heard of the "lost masters".
Eraqus: Nope, where'd you hear that?
Xehanort: On that land shall darkness prevail and light expire.
This is followed by a black screen and a flash of the Roman numeral III from the Kingdom Hearts III logo. Xehanort then asks, "But you knew that, didn't you?" The Roman numeral III from the logo flashes again, followed by the note that the game is "Now in Development".
The trailer begins with a young Xehanort and Eraqus playing chess at the Land of Departure. Xehanort asks Eraqus of the Keyblade War, which Eraqus claims is "the master's favorite story." Xehanort then discusses the lost masters, who started the Keyblade War. While Eraqus feigns ignorance, Xehanort is unconvinced, telling him to "drop the facade." The trailer then cuts to a gameplay montage, featuring Sora, Donald, and Goofy as they battle new and familiar enemies at Olympus Coliseum, the Kingdom of Corona (based on Tangled), and Twilight Town. During the montage, Sora is shown with two new Keyblades, a new outfit, new and old abilities, Keyblade transformations, and Attraction Flow.
The final moments of the trailer cut back to Xehanort and Eraqus's game. As Xehanort reflects on the land where the Keyblade War was fought, he gazes at his future Keyblade and admits the future has been already written. An optimistic Eraqus, though, counters that light may prevail in the end, and that Xehanort might be surprised. Xehanort then expresses interest in this possibility.
As the camera lingers on the duo's kings, showing their game has ended on a stalemate, the game's logo is shown.
Jump Festa 2016
This trailer showcases gameplay across Twilight Town, Olympus Coliseum, and the Mysterious Tower. Sora's combat abilities are shown, demonstrating the return of Attraction Flow, Flowmotion, Shotlocks, and combos reminiscent of Kingdom Hearts II.
This trailer showcases combat at Olympus Coliseum, revealing Sora battling enemies alongside Donald, Goofy, and Hercules. It demonstrates the various combat options Sora has, including Shotlocks, Limits with Goofy, and Situation Commands. The trailer also reveals elements of the story, such as Maleficent and Pete searching for the Black Box last seen in Back Cover and Xemnas persuading Sora to use the power of darkness to revive Roxas.
D23 2017 Trailer
The trailer begins with gameplay in Twilight Town and Olympus Coliseum. All the while, the game's tagline appears in giant letters, then in normal-sized letters. It then fades into an introduction to the Toy Story-based world, where Sora strikes an alliance with Woody and Buzz. Gameplay set in the world follows, with Sora debuting new Keyblade transformations and the ability to commandeer vehicle-shaped enemies. Later, Sora encounters Young Xehanort, who muses on the world and how hearts connect. The trailer then ends with the logo and a release date of 2018.
D23 Expo Japan 2018 Monsters, Inc. Trailer
The trailer begins in the Kingdom of Corona, where Marluxia confronts Sora, Donald, and Goofy, confirming he is part of the True Organization XIII, even though Sora has no memory of him due to his previous memories being erased. It then cuts the Toy Story-world where Woody, Buzz, Rex, and Hamm prepare to ambush some Heartless before Sora, Donald, and Goofy appear. It then cuts to a world based around Monsters, Inc. where Sora and the gang meet Mike, Sulley, and Boo. After more gameplay is seen (which also confirms Ariel as a summon character), the trailer ends where Sora is confronted by Vanitas, also a member of the True Organization XIII, who comments about where Ventus' heart had slithered off to.
2018 Microsoft E3 Conference Trailer
The trailer opens in the kingdom of Arendelle with Sora defeating a Soldier Heartless before commenting on the cold weather, then spotting Queen Elsa as she flees across the fjord, turning it to ice in her wake. The next scene shows Sora, Donald, and Goofy meeting up with Olaf, then joined by Kristoff and Anna as she asks if Olaf knows them, only for Olaf to say he doesn't. As the trailer continues, Elsa saves Sora from a reindeer-like Heartless with her powers, but when Sora comments on how awesome they are, Elsa turns away from him and explains her powers are more of a curse than awesome. Sora then is seen trying to help Hercules save several civilians from being crushed by a large slab of debris Herc is holding up with his strength, stopping a large toy Heartless from attacking Hamm as Woody dives in to pull Hamm to safety, and fleeing with Mike, Sulley, and Boo as a CDA helicopter flies overhead among the inferno engulfing Monstropolis. Sora is then seen confronting Ansem, Seeker of Darkness, and Xemnas regarding Roxas outside the Old Mansion in Twilight Town, and confronting Larxene back in Arendelle as she mentions Elsa and her possibility of going down the path of darkness, which Sora vows to prevent. The final scene shows Riku in the Dark Meridian as a figure cloaked in darkness picks up a Keyblade. Mickey recognizes the voice when it speaks, and as the darkness disperses, it is revealed to be Aqua, having succumbed to the darkness as her blue eyes and blue hair now bear similarities to Master Xehanort's.
Unlike Kingdom Hearts II, Sora, Donald, and Goofy are redesigned with pirate outfits and their models are slightly more realistic and detailed (ex. Donald has noticeable feathers, Goofy has noticeable fur).