Square Enix has recognized that the story line could be slightly confusing with the debuting of so many new characters Kingdom Hearts III, the company has released a slew of videos explaining where the story is at.
Unfortunately the videos are in Japanese as Square Enix hasn't released English versions as of yet. Each video is displayed in the form of a narration throughout an animated book, showcasing the Chapter of Departures, Chapter of Memories, Chapter of Twilight, Chapter of Darkness and Chapter of Dawn.
We very much hope that Square Enix re-releases these animated videos in English as the videos are high-quality and provide a lot of vital information that could tie-up some loose ends for some people. Kingdom Hearts III will be released into the Western markets on January 29th 2019.