The maintenance passage was narrow and steep, filled with volcanic sulfur and the machine-oil smell peculiar to metal pipes. Almost tangible waves of heat kept surging up from below, evaporating their sweat as soon as it seeped from their skin. Supporting each other, Lin Yan and Zoro climbed down the nearly vertical metal ladder.
"This damn place... is worse than a steamer." Zoro spat, sweat stinging his wounds.
"The core of the Volcanic Factory... is right below." Lin Yan panted, pain throbbing through his chest and abdomen. The lingering force of King's punch, along with the backlash from forcing out Concept Collapse Fist and a miniature rule rewrite, had left him in terrible shape. But he had to hold on. Ace was down there, along with the Heart of the Furnace.
Robin's voice came from below through the communicator. "I see you. There's a platform at the end of the ladder. Be careful. Some defensive mechanisms are still active here."
The two carefully landed on the platform. It was a metal platform at the edge of a vast underground space. Below lay a bottomless abyss glowing dark red, with hot winds howling through it. Opposite them, embedded in the volcanic rock wall, stood an ancient structure of breathtaking grandeur. Built from enormous, regularly shaped black stone blocks, its style differed completely from anything in Wano Country or any other known civilization. Intricate geometric patterns and unknown writing covered its surface. Several immensely thick metal pipes extended from the structure, connecting it to the Onigashima factory district above and the boiling Lava Pool farther below.
This was the Ancient Factory, one of the secrets the Kozuki Clan had guarded for generations.
"These characters... some are variants of the writing on the Poneglyphs, but older, closer to the source." Robin stood at