Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.
Princess Syalis and her body double
The princess will send out Cubey to return to Goodereste Castle in her stead so that she can continue her vacation in Demon Castle when the Hero's journey comes to an end or they make negotiations for an alliance. They've done it before in the Homecoming Story Arc except the leaving part. But well, one can only wonder how long will everyone in Goodereste realize that the Princess with them is actually not their princess.