I am a Hero

A mentally unhinged manga artist witnesses the beginning of a zombie outbreak in Tokyo, and he’s certain of only two things: he’s destined to be the city’s hero, and he possesses something quite rare in Japan—an actual firearm! 
(Source: Dark Horse)
Notes:
Nominated for the 3rd and 4th Manga Taisho Award (2010).
Includes a new epilogue chapter that was released 4 years after the official end of the manga.