The Lingering Sentiment is an optional boss in Kingdom Hearts II: Final Mix+ and a temporarily playable character in Kingdom Hearts: Birth by Sleep. It is revealed that he is what remains of Terra once his body is taken by Master Xehanort.
 Journal Entries
 Kingdom Hearts II
A man connected to the portal which appeared in Disney Castle.
The armor covering his body can master the Keyblade's power much more than Sora can.