A secret trailer in the first Kingdom Hearts and Kingdom Hearts Final Mix hinted at the possibility of a sequel. Rumors for a sequel on the PlayStation 2 were spurred in Japan when a Japanese video game site, Quiter, stated that "an internal (and anonymous) source at Square Japan" confirmed that development of Kingdom Hearts II had begun. It was not until Kingdom Hearts II was announced, along with Kingdom Hearts: Chain of Memories, at the Tokyo Game Show in September 2003 that rumors were confirmed. Initial details were that it would take place some time after Kingdom Hearts: Chain of Memories, which takes place directly after the first game. Other details included the return of Sora, Donald, and Goofy, as well as new costumes. At the 2004 Square Enix E3 press conference, the producer, Shinji Hashimoto, stated that many mysteries of the first game would be answered.
