Seiji Sasa hits the train station in this northern Japanese city before dawn most mornings to prowl for homeless men. He isn't a social worker. He's a recruiter. The men in Sendai Station are potential laborers that Sasa can dispatch to contractors in Japan's nuclear disaster zone for a bounty of $100 a head. "This is how labor recruiters like me come in every day," Sasa says, as he strides past men sleeping on cardboard and clutching at their coats against the early winter cold. It's also how Japan finds people willing to accept minimum wage for one of the...