The door was sealed. The stone slab, wedged tight with Black Iron shards, blocked the exit to the surface trench.
For the first time in six months, Ji Han was in total darkness.
"Light it," Ji Han said. His voice echoed in the cramped, wood-lined corridor of the Granite Tunnel.
Lin Qinghe struck the flint they had scavenged from the river stones against a piece of Black Iron. A spark jumped into the pile of dried root shavings.
Whoosh.
The "Root Charcoal" caught instantly. It didn't smoke; it burned with a clean, intense blue-orange flame, releasing the stored solar energy of the Long Day.
The light flickered, casting dancing shadows against the walls lined with stacked tubers. The tunnel, once a mine, now felt like a wooden cabin buried in the earth.
Ji Han sat near the fire, extending his hands toward the warmth.
"The creatures outside," Ji Han murmured, looking up at the sealed ceiling. "The barrier stops them from entering, but the sun..."
"The sun did not discriminate," Lin Qinghe said, staring into the flames. "The Golden Barrier stops physical intrusion, but it does not stop light or heat. The 'Long Day' turned the entire plain inside the barrier into a convection oven."
"So they cooked?"
"They were radiated," she corrected. "The Yang Fire of a stationary sun is not just heat; it is spiritual radiation. The beasts outside the barrier, the ones frozen in time? They are dead. Boiled in their own skins. The ones inside the barrier, if any survived the initial purge? They are dust."
Ji Han nodded grimly. The user's intuition was right. The heat had sterilized the world.
"So we are alone," Ji Han said. "Just us and the cold."
"And the things that slept through the heat," Lin Qinghe whispered.
As if on cue, a sound vibrated through the floor.
It didn't come from the surface, where the wind was howling like a banshee, sucking the heat into the void of space. It came from below.
From the Yin Hollow.
Ji Han pressed his ear to the granite floor.
Scritch. Scritch. Tap.
It was faint, muffled by the twenty meters of rock and the sealed stone door they had placed over the cavern entrance, but it was there.
"They're awake," Ji Han realized.
"The temperature inversion," Lin Qinghe explained, her face pale in the firelight. "During the Day, the surface was hot, and the hollow was cold. The Yin beasts stayed deep, hiding from the Yang. But now..."
"Now the surface is freezing," Ji Han finished. "The gradient has flipped."
"The Yin beasts thrive in cold, but they hunt Qi," she said. "And right now, this fire—and our bodies—are the brightest, hottest sources of Qi in the entire domain."
Ji Han looked at the Frost-Iron Cleaver resting against the wall.
"We aren't hiding from the cold," Ji Han said, gripping the hilt. "We're bait."
The scratching grew louder. It wasn't just one set of legs anymore. It sounded like rain. A thousand chitinous legs tapping against the underside of the world.
The Frost-Bone Centipede they had killed was a Level 1 Beast—a guardian. But guardians usually guarded a nest.
"The fire," Ji Han ordered. "Keep it small. If we make the tunnel too hot, we signal every predator in the bedrock."
He stood up and walked to the downward slope of the spiral tunnel. He placed his hand on the wall.
He could feel it. The cold was rising from the deep like a tide.
"Six months of night," Ji Han whispered. "We just have to hold the door."