The moment the raft struck the rocky ridge, Chen Hao was thrown forward, his knee hitting the edge of the plank, causing him to gasp in pain. Ignoring his leg, he reached for the latch on the waterproof storage compartment, and with a sharp pull, the lid snapped open.

"They're still here!" He breathed a sigh of relief and reached out to pull out the sealed boxes. Six samples were neatly stacked inside, the eerie blue glow of the fluorescent vines shimmering faintly through the container walls, as if responding to his touch.

Nana stood at the stern of the raft, her arm slightly raised, a thin beam of light shooting from her palm across the cabin structure. "The frame is slightly deformed, but the sealing performance is not affected." She paused, "Your knee joint experienced an impact of about three hundred Newtons; I recommend applying a cold compress to the area."

"Cold compress my foot, there isn't even a refrigerator here." Chen Hao stood up, bracing himself against the wooden plank, and stretched his legs. "Besides, what's a little pain? Last time I squatted in the toilet for too long, standing up was like the world spinning."

Nana didn't reply, but simply leaped lightly onto the shallows, her metal feet sinking half an inch into the mud. Once she was firmly on her feet, she turned back to look at him.

Chen Hao gritted his teeth and dragged the raft to the shore. Muddy water soaked his shoes and clung to his socks. He laughed between breaths, "We came back looking like scavengers, the kind who just got chased by the city management officers."

“According to data analysis, your current appearance is 72% similar to that of a ‘scavenger’,” Nana said calmly. “The main characteristics include muddy clothes, worn-out shoe soles, and a crooked backpack.”

"Hey, can you stop trying to intimidate me with data all the time?" He secured the raft and patted the hatch. "I brought back so many treasures, can't you at least say 'thank you for your hard work'?"

"Your entire operation process has been recorded in the mission log." She turned and walked towards the base, "including three correct pole vaulting maneuvers, two obstacle avoidance maneuvers, and one successful sample preservation."

Is this a compliment or a way of checking in?

"This is a statement of fact."

Chen Hao rolled his eyes, picked up his backpack, and followed. After walking a few steps, he suddenly stopped and looked up at the road ahead.

The outline of the base gradually became clear in the dim light. A few lamps powered by recycled batteries hung on the exterior wall of the main house. The light wasn't bright, but it was enough to make out a newly carved mark on the door frame—a mark left when they first successfully lit the pottery stove. Dried vines were piled in the corner, and several rough pottery cups filled with rainwater collected the night before sat on the windowsill.

“How long have we been here?” he asked.

“The exact time is sixty-seven days, ten hours, and thirty-nine minutes,” Nana replied, “starting from the activation of the energy module.”

"It sounds like being in jail," Chen Hao grinned. "But why do I feel like it's more like home than school?"

Nana glanced at him, a blue light flashing deep in her pupils, but said nothing.

The two entered the base through the gate, and Chen Hao casually placed his backpack on the long table with a muffled thud. Several hand-drawn maps were spread out on the table, next to a half-pencil and an empty can. He went around to the kitchen area, opened a homemade bamboo cabinet, and took out two bowls.

"We'll have an extra dish tonight," he said. "The crystal fragments I brought back can be ground into powder and mixed into the soup to supplement silicon."

“The human body does not need to supplement with silicon dioxide,” Nana said, standing at the doorway. “Besides, this substance is not edible.”

“I know.” He scooped a spoonful of water into the pot. “I just want some peace of mind. Look, others drink chicken soup, but we’re drinking ‘Essence of the Earth’ soup.’ Sounds so fancy.”

Nana walked to the workbench and began to unpack the sealed container used for collecting samples. "I recommend prioritizing the treatment of plant secretions," she said. "Their antibacterial properties may be useful for wound care."

"Okay, then you go ahead with your work, I'll take care of improving the quality of the food." Chen Hao hummed a song as he walked towards the stove, pausing as he passed the planting area.

One section of the fence was loose, and the vine rope between two wooden stakes drooped down, with several fluorescent grasses peeking out cautiously. "Oh dear, are these little devils trying to escape again?" He squatted down to re-tie the rope. "If they run out again, they'll all be dead plants by tomorrow morning."

"The fence is maintained every fourteen days," Nana's voice came from behind. "It's been eighteen days since the last inspection."

"So you mean I missed the deadline?" He tightened his knot, clapped his hands, and stood up. "I can't help it, I've been too busy lately, rowing and dodging rocks, I don't have time to be a gardener."

"I can generate a list of automatic reminders."

“No, I get stressed when you make plans.” He waved his hand. “Let me maintain a relaxed feeling of being ‘ready to collapse but not yet’.”

Nana paused for a moment, then suddenly turned towards the kiln. "There's a longitudinal crack on the inner wall of the kiln, twelve centimeters long and three point seven millimeters deep." She approached to examine it. "Continued use may cause a 19% decrease in thermal efficiency."

Chen Hao leaned closer to take a look and frowned: "This thing might suddenly explode, right?"

"The probability is less than 4.3%."

"It doesn't sound like a high-risk job, but if it really explodes, we'll have to switch careers and become charcoal drawing models."

"I suggest using a mixture of clay and quartz sand for filling," she said, bringing up the projector interface. "The material ratio is three to one, and it needs to be air-dried for six hours after application."

"It's waiting again." He sighed. "What we have in abundance here is 'waiting.' Waiting for dawn, waiting for the wind to stop, waiting for the water to boil... It feels like I've spent most of my life waiting."

"Your heart rate dropped by an average of 11% during the waiting period, indicating that you were in a relaxed state."

“I had no choice.” He scratched his head. “But then again, even though these things are old and worn out, we built them bit by bit. I used to be too lazy to even clean under my bed in the dorm, but now I can actually keep an eye on a kiln and worry about whether it has cracks.”

Nana turned to look at him: "You have completed the cognitive shift from passively surviving to actively building."

"Translate it into human language?"

"You're starting to care about this place."

Chen Hao paused for a moment, then laughed. He walked to the steps outside and sat down, looking at the crooked but fully functional small buildings in the base: clothes racks, rainwater collection troughs, tool sheds... even the toilet had a sign that read "No bargaining," I wonder who had the time to carve that.

“Actually,” he looked up at the faint light shining through the rocky roof, “I used to think that living was all about enjoying life, eating well, sleeping well, and playing games, and nothing else mattered. But now? I’m eating wild vegetables every day, repairing broken walls, and figuring out how to make the lights stay on for five more minutes, and I actually feel… quite fulfilled.”

“This state aligns with the ‘goal-driven satisfaction’ model,” Nana said, standing beside him. “When an individual consistently completes quantifiable tasks, the brain releases dopamine.”

"Can't you just say 'you've become more reliable'? Why do you have to use these technical terms?"

"I am stating the facts."

“Facts also depend on the context.” He pointed to the workshop in the distance. “Look at that building. It started as just a rain shelter, but now you can hammer nails into it. And look at that vegetable garden over there. The first crop all died, the second crop grew crookedly, but the third crop was finally edible. Aren’t we… getting stronger little by little?”

Nana raised her hand, projecting a holographic image from her palm: a modular living unit design, a water purification path, a tool classification and storage scheme, and an optimized lighting layout...

"This is a six-month development path based on existing resources," she said. "If implemented, the base can achieve energy self-sufficiency, stable food supply, and enhanced emergency response capabilities."

Chen Hao stared at the image for a long time, then suddenly reached out and poked the "residential area expansion" section on the projection. "Is this 'phased expansion unit' what I meant by 'building a big house'?"

"yes."

"Does 'crop rotation + lighting optimization' mean 'growing a lot of vegetables'?"

"yes."

He laughed heartily: "You actually took my sleep-talking seriously?"

“All expressions are sources of information.” She put away the projector. “The difference lies in whether they are actionable.”

"So you blew up the balloons in my head and turned them into kites that can fly?"

"The analogy is somewhat misunderstood, but I accept this interpretation."

Chen Hao stood up and dusted off his pants. "So what's next? Do we have to build a gym so I can lose weight?"

"Your body fat percentage is still higher than the standard value."

"I knew you'd bring this up!"

"This is an objective fact."

"Alright, alright, once I build the new house, the first thing I'll do is install a 'shut up' switch for you." He laughed and walked into the house. "But... can you really make all of this happen?"

Nana followed behind him, her voice steady: "As long as you don't give up halfway."

"Me?" He turned around and glared at me. "When have I ever given up? I didn't run away during the last landslide, and you think I'd just abandon this little thing?"

"You once complained for 43 minutes about the lack of seasoning in your breakfast."

"That's different! A person can be poor, but they can't eat without any flavor!"

"Logical contradiction: You ate stewed vegetables without seasoning for five consecutive days last week."

"That's a special case!"

“The records show that you said, ‘This soup is as bland as my life.’”

"...Are you deliberately trying to sabotage me?"

A faint blue light flashed in Nana's eyes.

Chen Hao shook his head, walked into the main room, and plopped down on a low stool by the table. He picked up the small notebook, turned to the last page, and found it blank.

He stared at the paper for a while, but didn't write anything.

Nana stood across the table, the future plan reappearing in her palm. The lines were clear, the sections well-defined, and each module was marked with a timeline and required materials.

Chen Hao looked up and grinned: "Do you think if we build all of these, people will come to visit? How about charging a battery for admission?"

"There are currently no records of human visitors."

“Then let’s use it as an advertising slogan.” He stood up, leaning on the table. “‘Welcome to Underground Civilization Base No. 1. Here you’ll find lights that don’t need electricity, food that lights up on its own, and a robot tour guide who will always remember your embarrassing moments.’”

Nana looked at him quietly.

Chen Hao walked to the door and looked out at the dimming light. The wind blew through the clothesline, making a slight creaking sound.

He suddenly said, "Next time I explore, I want to try going south."

Nana pulled up the map: "The geological structure of this area is unstable, and the risk of collapse is high."

“But there’s a question mark on the map.” He pointed to the corner of the projection. “You’ve probably seen it too—there might be a larger space there.”

"The risk factor exceeds the safety threshold."

“But we came here to find something, didn’t we?” He turned around, his eyes shining. “Those plans you mentioned need more resources to come to fruition, right? How long will it take us to build them with just these few broken stones and rotten vines?”

Nana remained silent for a few seconds.

Blue light slowly flowed in her eyes.

When she spoke, her voice remained steady, but it lacked some of its mechanical quality.

“If you’re going,” she said, “you’ll at least need to get a new pair of shoes.”