In the early days at Disney, the idea for Kingdom Hearts was regarded by some as an “abomination”. Instead of the typical licensed game, it wouldn't focus on highlighting one particular title, but rather would be a crossover between fifty years of Disney properties. Even riskier to their brand was Square Enix 's proposal to use their own Final Fantasy characters and have them interact with fan-favourite figures like Donald and Goofy. It got even more bizarre when game director Tetsuya Nomura walked into a meeting with a picture of the new protagonist Sora wielding a massive chainsaw. This was terrifying for Disney, who had become known in the industry for being strict with licensing out their characters.

The whole Kingdom Hearts project was a leap of faith for Disney. At the time, Buena Vista Games (now the defunct Disney Interactive Studios) was at a crossroads, only gaining a following through the increasingly unprofitable educational game market. It was decided that Buena Vista would quit publishing games themselves and focus on licensing Disney properties for other publishers. But as Buena Vista Games general manager Graham Hopper recalls, many of the licensees they were working with were producing low-quality games for a quick profit. Therefore, Square Enix 's (then Square) interest in developing a new IP together was an opportunity for Disney's game team to collaborate on something with long-lasting success.

But what the newly appointed director Tetsuya Nomura wasn't interested in was making someone else's idea. When he entered his first meeting, Disney staffers presented all of their potential game ideas to him. This likely would have been normal for a licensing meeting where Disney shares the available licenses that would make popular games. But Nomura was unique in that he rejected all of the ideas presented to him and discussed his own idea, inspired by Super Mario 64, where an original character journeys through several Disney worlds.

Nomura got his way in the end, but with one very large stipulation: They couldn't use Mickey Mouse. Before Nomura was attached as director, it was Square Enix 's hope that they could produce an RPG with Mickey Mouse as the main character, but Disney were particularly protective of their company mascot. This is a frequent practice when licensing out original characters. Some companies don't want anyone else to use their characters at all, sometimes they just don't want them to be using certain items and other times, they'll have very specific rules. In the case of Mickey Mouse, Disney allowed him to appear only once, shown from a distance. Nomura decided to use this one opportunity for a final scene where he has his back to the camera and helps Sora seal the door to Kingdom Hearts.

Although Kingdom Hearts was an original concept by Tetsuya Nomura , in an effort to protect Disney's brands, the IP itself and any original characters developed during the series would belong to Disney. This meant that both Buena Vista Games and Disney would have the authority to veto any creative decisions, even if those decisions didn't involve original Disney characters. With that said, Disney has been remarkably hands-off when it comes to the overall plot of Kingdom Hearts, recognising the importance of Nomura's creative freedom. Square Enix didn't get everything they asked for in Kingdom Hearts, but even though there were some at Disney who were skeptical about the project, they received the support needed to continue. Even Disney president Bob Iger approved some controversial aspects of the production.

Once the Kingdom Hearts concept had been decided on and the basic rules were established, licensing the individual worlds was fairly straightforward. Most of the brands the Square Enix team were looking to include weren't recent properties and were properties that Disney had full ownership of. The one exception was Disney's Tarzan, which is owned by both Disney and Edgar Rice Burroughs Inc. The original author Edgar Burroughs established the company in 1923, and his family have used it as a way of controlling the Tarzan license. The Tarzan world “Deep Jungle” has not appeared in any of the Kingdom Hearts sequels.

After the first title, licensing became easier thanks to the success of the Kingdom Hearts brand. Square Enix was able to command more trust and sought access to more Disney properties for Kingdom Hearts II. One of the largest changes was the addition of Mickey Mouse as a main character. Not only was he now shown throughout the game, but the staff collaborated with Disney on a new outfit that established him within the Kingdom Hearts universe. This was Square Enix 's main demand and it was only once they'd received permission to feature Mickey Mouse more heavily that they started production.

One of the other things Tetsuya Nomura wanted was permission to create a world based on a live action film. He'd already decided on using Tron after seeing a Disney Interactive Studios staffer working on a Tron game (likely Tron 2.0) on his PC, but Nomura wanted to show a more detailed live action world using Square Enix 's latest realistic capture technology. He compiled a list of films he'd be interested in adapting, and although his first choice was rejected, Disney was happy to see a Kingdom Hearts version of Pirates of the Caribbean.

Although entering into the Kingdom Hearts franchise with Disney has meant going through several approval processes, the benefits can outweigh the negatives. Although Kingdom Hearts frequently features several different areas outside the pre-established worlds of the films, access to original character designs and behind-the-scenes materials has made it easier to develop accurate 3D models and environments.

But even more valuable is Disney Character Voices International , a global company that manages the voice dubbing for all Disney properties. This allowed Kingdom Hearts to feature performances by much of the original casts of these Disney films in both English and Japanese. This meant that Jim Cummings returned to his role as Winnie the Pooh and Tigger, cabaret singer Ken Page reprised his role as Oogie Boogie (The Nightmare Before Christmas) and even Kathryn Beaumont, who voiced Alice (from Alice in Wonderland) at the age of 13 returned to voice the character over 50 years later. When future projects arise, Disney Character Voices allows the first right of refusal to the original voice actors. It's only when they refuse do they contact “sound-alike” voice actors. For example, Robin Williams would have been offered the chance to play the Genie in Kingdom Hearts, but he'd refused, so it was handed over to Genie backup voice actor (and the voice of Homer Simpson) Dan Castellaneta .

Even though Disney was able to keep strong relationships with their voice actors and developer Square Enix , they did drive away theme song performer Hikaru Utada . In an interview with JETANNY in 2009, Utada claimed that she was underpaid by Disney for the theme songs to the first Kingdom Hearts and Kingdom Hearts II (which she wrote and performed in both English and Japanese). Her father and producer Teruzane Utada, stated that they had turned down Disney for this reason. This is likely the reason that there haven't been new opening themes since Kingdom Hearts II. However, their relationship with Disney seemed to have improved in recent years with Teruzane Utada claiming their involvement in Kingdom Hearts III was undecided, and in February 2018, a new trailer was released featuring Utada Hikaru's newest song, “Don't Think Twice.”

This wasn't the only relationship that Disney had to repair since the original Kingdom Hearts game. Back when the series started in 2002, then Disney CEO Michael Eisner had a famously bad relationship with the late Pixar Chief Executive Steve Jobs. At the time, Disney and Pixar were two separate companies that collaborated on films like Toy Story and Monsters Inc. It was later reported that Eisner had sent messages to the Disney board disparaging Pixar, in particular the 2003 release of Finding Nemo, stating that it was just “OK” and that he believed it wouldn't be popular. Partly in response to this, Walt Disney's nephew, Roy Disney, staged a “Save Disney” campaign to oust Eisner as CEO of Disney.

Michael Eisner resigned as Disney CEO in September 2005 and was replaced by Bob Iger. Soon after becoming CEO, Iger made the decision to purchase the animation studio and put Pixar animator and producer John Lasseter in charge of all of Walt Disney Animation. This was a decision that Tetsuya Nomura later praised in a 2014 interview with Famitsu, stating that, “Now that John Lasseter has been made chief creative officer at Disney, there will be even more ambitious works.”

Thanks to their repaired relationship with Pixar, Disney has been able to effectively help them collaborate with Square Enix for Kingdom Hearts III, the first console Kingdom Hearts to feature Pixar characters. They were given access to exclusive 3D production materials, which the staff at Square Enix found easier to develop into the game's graphics as opposed to their usual task of adapting 2D characters into the 3D game. Lasseter visited Square Enix himself during the development to offer some suggestions for what to include in the Toy Story world.

Note: John Lasseter left Disney at the end of 2017, following reports of sexual misconduct. Lasseter would harass female staffers by “grabbing, kissing [and] making comments about physical attributes”. His actions and attitude left a culture of sexism unchecked at Pixar that drove out female talent. He has been replaced by Frozen director Jennifer Lee at Disney and Inside Out director Pete Docter at Pixar.

But the Pixar staffer whom Square Enix would have had the closest interactions with was Kingdom Hearts fan and associate creative director Tasha Sounart. To help with the development of Kingdom Hearts III, she was assigned as Pixar's consultant. Sounart worked with both Square Enix and Pixar staff to develop accurate representations of their brands as well as to improve the game itself. Square Enix would develop the original ideas and she would then work with Toy Story character designer Bob Pauley to create ideas for Sora, Donald and Goofy's Toy Story forms, the themed keyblade and the environments.

Pixar and Square Enix 's collaboration sometimes caused cultural differences to become apparent. Being an animator herself, Tasha oversaw cutscenes and character animations as well as the character models themselves. She noted that sometimes the staff at Square Enix would make the Toy Story characters use Japanese expressions and mannerisms, and she'd remind them to use American expressions instead.

With Kingdom Hearts III, the team has started to seek even more licenses of recent properties. Even the most precious current Disney properties have become the target of an incredibly passionate staff. Nomura noted that of all the properties they were dealing with, Frozen had the most guidelines that they had to follow. Despite this, Nomura became set on including the world after being treated to a private advance screening of the film.

Like with Pixar, the Square Enix team has been in close contact with Disney Animation producers and consultants working to best represent their films. One such producer is Roy Conli, who worked with the Kingdom Hearts III team to accurately replicate the worlds of his films, Tangled and Big Hero 6. Because of this collaboration, the teams could work together to develop a new story that takes place after the events of the film that fit into both the Big Hero 6 and Kingdom Hearts universes.

Conli has been so impressed by Square Enix 's work adapting his films that he announced their inclusion himself. He even references his physical resemblance to series villain Master Xehanort (something that Square Enix staff pointed out to him).

Although Disney and Square Enix have always been close, it's become clear that Kingdom Hearts III is the most ambitious step in their relationship yet. During the years spent working on Final Fantasy Versus XIII (now Final Fantasy XV) and other projects, Nomura had been repeatedly asked by both Kingdom Hearts fans and Disney itself about making the next numbered installment in the Kingdom Hearts series. Kingdom Hearts was an attempt for Disney at “broadening their reach to new and older audiences throughout the world” and judging from the series' financial success, it worked. Then general manager of Disney Interactive Graham Hopper even credited the success of Kingdom Hearts in preparing Disney for renowned game designer Warren Spector's creative interpretation of Mickey Mouse for his game Epic Mickey (which went on to sell over 2 million units).

Disney has rarely had successes within the video games market, being one of the few divisions within the company to be frequently making a loss. A lack of risk-taking, little knowledge of the video game market, and strict oversight are regarded as major reasons for the failure and eventual closure of Disney Interactive Studios in 2016. But even with the failure of their own properties, the team was spurred on by the success of Kingdom Hearts; then-Disney Interactive vice president John Vignocchi had a Kingdom Hearts themed wedding, they included a keyblade in toys-to-life game Disney Infinity 3.0, and they frequently used Kingdom Hearts' name to sell their other properties.

Although Disney Interactive may no longer exist, Kingdom Hearts III has secured a direct relationship between Tetsuya Nomura 's team at Square Enix and the creators of the animated films they seek to adapt. As Kingdom Hearts grows in popularity, so does the fanbase of the series within Disney. With Square Enix 's ability to impress the original creators with their versions of Disney and Pixar films comes more future possibilities for ambitious collaborations and stories.

Thanks to all the journalists and translators for helping to make this information publicly available to Kingdom Hearts fans.