During the events of Kingdom Hearts: ReDive, join Sora along with his many new friends at the respective guilds in the exciting adventures during special seasons such as spooky Halloween, jolly holidays, fresh New Year, sweet Valentine's Day, meeting other people from another world, and much more.

In this alternate storyline, Sora takes the place of Yuuki from the Priconne series, as he encounters Ameth, a former navigational fairy, who guides him to the mysterious world of Astrum. In this realm, Sora joins a lively group of mostly female guild members on a quest, while uncover the source of a catastrophe that has altered the memories of all players, trapped in the game.

One day on a chilly December, Kamijou Touma and the others are planning to go to a family restaurant, however they stop at an event that hosts a beta testing of the newest game called 'Legend of Astrum', an VRMMORPG. Index gets tempted to play it and they 'luckily' were chosen to be one of the beta testers. Thus they log in...but later they notice it. They cannot log out anymore.