The sun did not move. It simply stopped.
According to Ji Han's internal calendar, it was Month 3, Day 20. The exact midpoint of the Long Day. The Solar Zenith.
For the last week, the shadows in the tunnel had vanished. The sun was positioned directly overhead, shooting a laser-straight column of "Yang Fire" down into the vertical shaft of their home.
The surface world was no longer a desert; it was a kiln. The temperature outside was high enough to boil water instantly. The azure grass was gone, turned to ash that coated the barren plains in grey dust. Even the rocks were cracking from the thermal stress.
Down in the tunnel, twenty meters deep, the heat was suffocating. The "cool earth" they had relied on for months was now radiating warmth like the walls of an oven.
"We have to retreat," Ji Han rasped. He was standing at the junction where the granite layer met the limestone cavity. His skin was red, slick with sweat that evaporated seconds after forming.
Above him, the spiral tunnel shimmered with heat haze.
"The Granite Layer has reached saturation," Lin Qinghe confirmed, her voice weak. She was already half-down the rope, descending into the Yin Hollow. "The rock is holding the heat. It will not cool down for weeks, even after the sun starts to descend."
Ji Han looked at his notches on the wall. The history of their survival—the first dig, the first grub, the first breakthrough—was being baked away.
"If we leave this open," Ji Han said, looking at the hole leading down to the hollow, "the hot air will rush down. It will mix with the Yin air."
"Thermal collision," Lin Qinghe warned. "It will create a storm. Fog. Rain. It might destabilize the temperature of the hollow."
"We need a door."
Ji Han grabbed the large slab of granite he had used as a practice anvil. It was heavy, irregular, and imperfect. But it was thick.
He dragged it to the edge of the breach.
"Go down," he ordered.
Lin Qinghe slid down the rope into the freezing darkness.
Ji Han took one last look at the upper tunnel. He could feel the Yang Qi pressing down on him—heavy, angry, and destructive. It was the power of the heavens, indifferent to the worms hiding in the mud.
He dropped through the hole, landing on the icy ledge of the limestone cavern.
The temperature shock was violent. He went from 60°C (140°F) to -10°C (14°F) in a second. His sweat froze instantly, forming a rime of frost on his skin.
He reached up and grabbed the granite slab from underneath. He pulled it into place, sealing the hole. He jammed Black Iron shards into the gaps to wedge it tight.
Darkness swallowed them. The only light was the faint, green pulse of the moss-stone in Lin Qinghe's hand.
"Sealed," Ji Han whispered, his breath clouding in the freezing air.
He sat down on the cold rock. Above the stone slab, the world was burning. Below it, the world was frozen. They were trapped in a bubble of ice, waiting for the star to move.
"Now," Lin Qinghe said softly, "we wait for the descent."
"Three months until sunset," Ji Han calculated. "Can we survive three months in the dark?"
"We have the centipede meat," she reminded him. "We have the water. But..."
She hesitated.
"But what?"
"The Yang is pressing down. The Yin is rising up to meet it. You are sitting at the boundary." She pointed to the stone slab sealing the ceiling. "The slab is hot. The air is cold. This is a crucible."
Ji Han looked up at the ceiling. She was right. He could feel the heat radiating from the stone "door," fighting the chill of the cavern.
"A crucible," Ji Han repeated.
He touched his chest. He was Qi Condensation Level 1. He had broken through using brute force. But his foundation was messy—a mix of "Wild Qi" from grass, "Earth Qi" from roots, and "Yin Qi" from meat. It was a patchwork of survival energies.
"I need to refine it," Ji Han realized. "I have the perfect oven."
He stood up. He walked to the center of the cavern, directly under the sealed entrance.
He stripped off his centipede-leather vest. He stood bare-chested in the freezing air.
"What are you doing?"
"Cultivating," Ji Han said. "The manual says to 'refine impurity.' I have Fire above and Ice below. I'm going to temper my body like the sword."
He assumed the Lotus Seat on the ice-cold floor.
He visualized the heat radiating from the slab above. Yang. He visualized the cold radiating from the pool below. Yin.
Inhale.
He pulled the heat down. It burned his meridians, fierce and aggressive.
Exhale.
He pulled the cold up. It soothed the burn, freezing the energy into place.
It was agony. It felt like being dipped in lava and then liquid nitrogen, over and over again. His skin flushed red, then turned blue, then red again.
But with every cycle, the chaotic energy in his Dantian grew smaller. Denser. Pure.
[System Notification: Cultivation Anomaly Detected.][Yin-Yang Tempering in progress.][Qi Density increasing.][Pain Tolerance increasing.]
Time dissolved. There was no day or night in the sealed hollow. There was only the heat of the Zenith and the cold of the Abyss.
Ji Han became a statue. He didn't eat. He didn't drink. He existed only to breathe the fire and the ice.
Days passed? Weeks?
Above them, the sun hung suspended in the sky, burning the world. But deep below, the "Worm Lord" was shedding his skin, forging a foundation that would survive the coming night.