Not sure how I didn't make this connection before... hopefully this isn't some well-known fact that I've just been missing.
In the Special Trailer, Yen Sid tells Sora and Riku that they have to awaken those in sadness and open the seven keyholes of sleep. "Those in sadness," of course, refers to the 7 mentioned in Mickey's letter to Sora at the end of Re:Coded - Terra, Ven, Aqua, Roxas, Xion, Axel, and Namine. There are 7 hearts in sadness and 7 keyholes of sleep... and Sora is going into the World of Sleep in order to awaken those hearts and unlock those keyholes. I reckon each keyhole (harbored in the 7 worlds that Sora visits in DDD - Nomura has confirmed that there will be 7 playable worlds to unlock in the Realm of Sleep) must unlock one of those 7 hearts, whatever that might imply.
Not sure how I didn't make this connection before... hopefully this isn't some well-known fact that I've just been missing.
In the Special Trailer, Yen Sid tells Sora and Riku that they have to awaken those in sadness and open the seven keyholes of sleep. "Those in sadness," of course, refers to the 7 mentioned in Mickey's letter to Sora at the end of Re:Coded - Terra, Ven, Aqua, Roxas, Xion, Axel, and Namine. There are 7 hearts in sadness and 7 keyholes of sleep... and Sora is going into the World of Sleep in order to awaken those hearts and unlock those keyholes. I reckon each keyhole (harbored in the 7 worlds that Sora visits in DDD - Nomura has confirmed that there will be 7 playable worlds to unlock in the Realm of Sleep) must unlock one of those 7 hearts, whatever that might imply.