Closed All Day

It's not a ghost, it's not a system. It's a set of templates - turning people into monsters. Food couldn't fill him up, and neither did water. He can only survive by sucking the life force out of others. The protagonist has two choices. Go into the mountains and starve yourself to death. Go to the city, find people, and hunt for food. He chose to live. Then he discovered that this set of templates allowed him to transform into the same kind. One, five, ten thousand - an army of absolute obedience.