Kingdom Hearts: Chain of Memories

Sora, Donald, and Goofy have defeated Ansem and restored the world. But beyond the dark door—a door that had to be closed—Riku and King Mickey remain. And so the trio set off again on a new journey to find Riku and the king. As they progress through the Castle of Oblivion, encountering agents from the mysterious organization along the way, Sora and his friends begin to lose their memories. What does it mean to hold, something dear? And in the end, what path will Sora choose?!
(Source: Yen Press)