Sora and his friends have returned home from their adventures and are finally settling down to spend time with their loved ones. However, when a new threat looms on the horizon as an old enemy allies with a mysterious new foe, they are brought together once again on a quest across even more worlds than ever before to determine the fate of all of Creation.

Luz Noceda sees a certain Thai girl in a news article discussing a frog world and an invasion. Realizing that the girl she had met before is also back on Earth, she decides to try and reach out to her. Anne Boonchuy receives a friend request from a girl she had seen step through a portal months ago. Shocked and glad to see her back on Earth, she hits Accept and sends her a message.

Kara Zor-El's pod crashes on Destiny Islands, where she is taken in as the adoptive sister of Sora. When the Heartless consume the Islands, Sora and Kara set out on their adventure together, to find Riku and Kairi and to make sure no other worlds fall to darkness. (Cross-posted on AO3)

The Guardians of Light celebrate Christmas at the Land of Departure. They open presents, take pictures, tell stories, have a magical airstepping snowball fight, and enjoy being together on the most magical day of the year.