Zombie Hunter 1-4

Unknown to the world, aliens have begun to invade people's bodies. A young race car driver named Toshio was contracted by a mysterious organization for a "test" for money. That test turned out to be a hellish training to become a Zombie Hunter. Toshio decided to return to a normal life instead, but soon was confronted by the harsh reality of a Zombie Hunter. Surrounded by shallow figures and aliens, Toshio accepts his new life as a Zombie Hunter …

(mangaka never finished the story)