An Oath to Return

"An Oath to Return" is the secret ending of Kingdom Hearts III Re Mind. Unlike previous secret endings in the series, there are two possible endings, with one being considered the "true ending", while the other is a "bad ending". The condition to unlock either ending depends on the outcome of Sora's battle with Yozora in the Secret Episode of Kingdom Hearts III Re Mind.

Like, Is Any of This for Real or Not?
If Sora wins the battle, Yozora stumbles backwards and begins to fade away into light. He muses that his powers aren't needed yet, but when Sora is confused, Yozora simply tells him not to mind before fading away, with a slight smile on his face. A bright beam of light engulfs Shibuya and sends Sora back into the Final World.

Meanwhile, Yozora is woken up in a car by his driver, who calls him "commander" and asks him if "it" is impressive. As Yozora looks outside the passenger window and reflects silently, he and Sora wonder if their fight was real or not before Sora then states that none of this makes any sense to him.

An Oath to Return

KINGDOM HEARTS

Characters in order of appearance

 * Yozora's driver can be heard waking him up in "Like, Is Any of This for Real or Not?".

Unlock criteria
In order to unlock "An Oath to Return", the player must finish the Limitcut Episode of Kingdom Hearts III Re Mind before being able to access the Secret Episode, where the player will be able to fight Yozora.

Trivia

 * When Yozora wakes up in the car, it is a shot-for-shot recreation of the opening to the  2011 trailer. Kingdom Hearts series creator Tetsuya Nomura was originally the head director for Final Fantasy Versus XIII.
 * The name of the cutscene for both endings and Yozora's and Sora's final lines echo Sora's first lines from the opening cinematic of the original Kingdom Hearts.