Though you'd expect a game about Goofy and Donald Duck saving the world to be straightforward, the lore behind the Kingdom Hearts series is just a wee bit dense. Square Enix knows it, too. That's why Kingdom Hearts director Tetsuya Nomura is working on a series of videos that summarize the story behind the Kingdom Hearts series. They should (hopefully) make the lore easier to understand.
Nomura talked about the upcoming series in a recent interview with Famitsu. There will be five videos / episodes, and the whole shebang will probably be a few hours long. The Japanese version of the story summary should be available soon on the Kingdom Hearts website. It'll reportedly be available in Kingdom Hearts 3 itself as well.
Slight correction, it appears this recap video is broken into 5 videos/episodes based on a new Famitsu interview with Nomura that came out after this tweet (@KZXcellent)— DKHF (@DKHF4) June 15, 2018
"I have no idea what the hell these games are about" is the number-one reason potential newcomers are scared away from the Kingdom Hearts games. While there are fan-made summaries galore, a focused story breakdown from Square Enix itself will be a valuable resource to point series newbies to—especially with Kingdom Hearts 3 on the horizon. It looks great, and the inclusion of new Disney properties like Frozen and Wreck-It Ralph has already piqued the curiosities of people who generally aren't into Kingdom Hearts games because they're so inaccessible (myself included, cough cough).
Still, though—a three-hour story summary? That just says it all, I suppose. For now, use our Kingdom Hearts 3 guide to wade through the information currently available about the game.