Poisonous Witch Doctor is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

The witch’s descent, David Sun, has decided to join the modern society after learning all the witchery and vermin from his master. He doesn’t have any goals other than his family’s well-being and earn some extra money by saving people from illness. He did not expect trouble to come to find him. While facing all the temptation and evil, watch how a fatty hides from others’ sight and promotes witchery..