Heart & Key

"Heart & Key" is the ending of Kingdom Hearts χ Back Cover. It uses in-game graphics and voice acting, and ends with the phrase "Reconnect. Kingdom Hearts". It serves as the true ending and acts as a prologue to Kingdom Hearts III.

Synopsis
Luxu stands alone in the Keyblade Graveyard, alongside the mysterious Black Box and No Name given to him by the Master of Masters. Luxu studies his new weapon for a moment, and he looks to the sky as he says, "May my heart be my guiding key."