Zombie hunter manga

Zombie Hunter summary:

Unknown to the world aliens have begun to invade people's bodies. A young race car pilot named Toshio was won by a mysterious organization for a "test" for money. That test turned out to be a hellish training to become a Zombie Hunter. However, Toshio decided to return to a normal life but soon face 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)