THE 3 HEARTS SLEEPING WITHIN SORA
>In the battle, each were put where they should be

As alluded in the Ansem Code and other sources, there are three hearts sleeping in Sora; two are specified as Roxas and Ventus in the story, but the third one's identity is not as clearly stated. However, given the content in KH Days and KH 3D, you can see it is Xion's heart. In this adventure, all three hearts return to their corresponding bodies and the inside of Sora's heart is finally put in order.

Image caption: Xion's heart returned to her body when Sora and the real Organization XIII's Xion clashed.