Q: While looking at the slides in Deep Jungle, Sora reacts to one slide in particular. The image of a castle feels familiar to Sora, even though he’s never been off his world. Why is this?
A: As revealed by the end of the game, Sora held Kairi’s captive heart inside him. Similarly to how he kept seeing her in various worlds, it is Kairi’s heart inside Sora that is reacting to the image of the castle as it reminds her of her original home, Radiant Garden/Hollow Bastion. This is also why Sora remarks, upon arriving at Hollow Bastion, that the world feels familiar to him.