I Am a Hero

(from ebookjapan):

The series has sold over 8.3 million copies! The gold standard of zombie manga, "I Am a Hero," is now available in a "complete edition" with a new cover design, reprinted color pages from the serialization, and over 80 pages of new artwork in the final 22 volumes! Witness the new ending of the story.

He is 35 year old who spends his time as an assistant to a mangaka, sometimes escaping into delusion in order to win over the agonizing reality. One day, however, a mysterious infection begins to spread without him noticing...and the real world begins to break down...⁉

He wanders into a world where the ordinary and the extraordinary, the mundane and the insane intersect. A personal survival panic horror story!

Official English

• Won the 58th Shogakukan Manga Award for General Manga in 2013

• Adapted into a Live Action film in 2016. Link to the ANN Page