This was the Chosei Coal Mine. From a pier on the coast, it stretched thousands of feet under the ocean. Like many of these mines, the conditions were horrific. The tunnels were dark, water seeped in, and the men could literally hear boats in the ocean above them. But even beyond just the conditions, maybe the most disturbing part was that many of the men who went in day after day were not there voluntarily. This is the story of Chosei Coal Slaves, and as always, viewer discretion is advised.