Batman: Death Mask(2008)

Batman: Death Mask

Issue 1: There's a new serial killer in Gotham, and he may have ties to the training Bruce Wayne acquired as a young man in Japan. Does the murderer know Bruce Wayne is the Batman

Issue 2: Bruce Wayne must confront his past and examine how the time he spent in Japan as a young man training to become Batman affected him...and whether his experiences then somehow led to the killer now rampaging throughout the underworld in Gotham.

Issue 3: The mystery of the deadly masks is uncovered, as the killer reveals his long-standing deep-rooted connection to the Dark Knight and the time they spent together as students in Japan years ago.

Issue 4: Events come to a head as the Batman must defeat the Oni — but before he can confront it, he must first face his own troubled past.

(Source: DC Comics)