Akumugari

Akumugari (悪夢狩り) is a manga series by Arimasa Oosawa with illustrations by Masato Fujisaki. It was serialized in Shounen Sunday Super.

Plot
The drug 'Nightmare' gives a drastic impact, changing a human physical to a gigantic creature. Then a man appeared to stand up against these creatures for the sake of prosperity and to prevent misfortunes of mankind.