D.Gray-man 3-in-1 Edition manga volume 9 contains volumes 25-27 and features story and art by Katsura Hoshino.

Allen continues his transformation into Nea, the mysterious Fourteenth inside him. When a shocking revelation from the Millennium Earl traps Allen in Nea's spirit world, he desperately seeks to understand the entity that's using him like a puppet. Perhaps his own past can offer some clues…