When Kingdom Hearts 3 was first announced, fans had hoped that the game would include content from both the Marvel Cinematic Universe and the Star Wars movies, but no characters from either franchise made an appearance. It turns out that there was a good reason for the lack of Marvel/Star Wars content in Kingdom Hearts 3 and it was due to legal issues.

Kingdom Hearts 2 was released in 2005, while Kingdom Hearts 3 was released in 2019. It was during that major gap between games that The Walt Disney Company purchased Marvel Entertainment (in 2009) and Lucasfilm (in 2012). Even before those acquisitions, characters from Disney's live-action movies or Square Enix's other games would appear in the Kingdom Hearts series. After so many memorable Disney cameos in the past, it was fair to wonder just how impactful the acquisition of Marvel and Lucasfilm properties would be on the future of the Kingdom Hearts franchise.

Related: Kingdom Hearts 3 DLC Is Coming

Fans dreamt of worlds based on Spider-Man or the Avengers, or that Sora would wield a lightsaber Keyblade, but as it turns out, that was much trickier than anticipated. Tetsuya Nomura was interviewed for the Kingdom Hearts 3 Ultimania guide, which has been translated into English and uploaded to KH13, and he was asked about the possibility of Marvel or Star Wars content appearing in future Kingdom Hearts games. Nomura explained that other companies own the licenses to develop games based on those franchises and that his team would need to make a separate legal agreement with them in order to use the characters or settings from Marvel or Star Wars: 

"...in order to change those [properties] into a game, contracts must be made with each company separately, and there are cases where other game companies already have contracts, so although the Disney Group has indeed added those [properties], incorporating them into KH isn't so simple."

Nomura explained that this was the reason why Mickey Mouse only briefly appeared in the first Kingdom Hearts, as another developer was working on a game using the Mickey Mouse license and they had to ask permission from them in order to show him in a silhouette. The closest thing to Marvel characters that could appear in Kingdom Hearts 3 was the Big Hero 6, but these were the Disney incarnations of the team that were inspired by the characters from the comics, rather than being a direct adaptation of them.

We know for a fact that EA is in current possession of the license to make Star Wars games and that deal doesn't seem to be ending anytime soon. The rights to make games using the Marvel license are controlled by a subsidiary of Marvel Entertainment called Marvel Games that distributes the licenses to different developers and publishers, which is why companies like Capcom and Square Enix are both able to make games using Marvel characters.

The dream of seeing Sora fighting alongside Jedi Knights or the X-Men seemed possible at one point in time, but it seems as if legal issues will prevent that dream from becoming a reality. It's possible that Nomura could push to use those characters in the Kingdom Hearts series (as he did with various Pixar licenses) but it seems unlikely to happen for now.

More: Kingdom Hearts 3 Director May Hold Back Future Worldwide Releases

Source: KH13