Goto Dengo begins climbing up the ventilation shaft. Halfway to the surface, it comes up into a network of small, rounded, interconnected chambers, whittled out of the rock, with fat pillars left in place to hold up the ceiling. The pillars are so thick and numerous that it’s not possible to see very far, but when the others have arrived, and Goto Dengo begins leading them from room to room, they learn that this system of chambers extends for a considerable distance.