The raft rocked gently, and a ripple spread across the water's surface. The crystal fragment that had been kicked into the water was nowhere to be seen.

Chen Hao stared down at the patch of deep blue ripples, his hand still on the pole, as if afraid that if he loosened his grip, something else might go wrong. He swallowed hard, his voice a little dry: "You scared me... I thought I stepped on a landmine."

Nana stood at the back of the raft, her gaze sweeping across the gradually widening river ahead. Her tone was calm: "No abnormal energy fluctuations, it can be determined to be natural environmental debris." She paused, "Your heart rate just increased by 18%."

"I was just excited." Chen Hao withdrew his foot, slowly sat back in the middle of the raft, and patted the storage compartment that was wrapped tightly in a waterproof tarpaulin. "This trip wasn't in vain." He grinned. "Do you think if we recorded this experience as a video and titled it 'Survival on a Wilderness Planet: A Terrifying Night on the Underground River,' it would go viral?"

“The dissemination effect is not within the scope of the task evaluation.” Nana looked ahead, “but your emotional expression matches the characteristics of ‘peak of achievement’.”

"Translate this—I'm pretty smug, aren't I?"

"This is the result of data analysis and does not involve emotional judgment."

Chen Hao laughed out loud, his shoulders shaking slightly, causing the raft to sway. He looked up at the receding rock face above him, the stalactites resembling rows of upside-down teeth in the dim light. "When I wrote social practice reports in school, I could never have come up with something this outrageous. My teachers would have thought I plagiarized science fiction."

“Every word you say now can be archived as the original log.”

"No, this is just my verbal explanation, not a formal report." He stretched, his bones cracking twice. "Speaking of which, we've really had one hurdle after another along the way."

Nana didn't reply, but her eyes flashed slightly blue as she calibrated the navigation data.

Chen Hao, however, did not intend to let her remain silent: "Do you remember when we first discovered the underground river? My first reaction was—'Oh no, even food delivery can't reach this place.'"

“Your exact words were: ‘If you go down this hole, you probably won’t be able to get out.’”

"Oh my, you remember that so clearly?"

“All key voice recordings have been archived.”

"Then take a look and see if there are any times when I praised you?" He tilted his head and glanced at her, "like 'Nana is so reliable' or 'Nana saved my life'."

There were seven positive reviews, three of which included exclamation marks.

"Okay, when we get back to base I'll apply for a banner for you that says 'Modern-day Lu Ban, Mechanical God of War'."

"I don't need any material recognition."

“Even if you don’t want it, I still have to give it to you, otherwise I’ll seem too ungrateful.” Chen Hao leaned against the edge of the raft, tapping his knee with his fingers. “But to be honest, if you hadn’t calculated the direction of the current, we wouldn’t have been able to build that raft at all. I’d probably be eating moss and waiting to die on the shore by now.”

"When you suggested using vines to tie the tree trunk, the structural stability was estimated to be only 32%."

"And then what happened?"

"After adjustments and reinforcement, it has been increased to 89%."

"See, that's the beauty of teamwork." He proudly raised his chin. "I come up with the ideas, and you're responsible for making sure they don't fall apart on the spot."

"Your ideas usually need to be revised twice before they can be put into use."

"Hey! At least it's a starting point." Chen Hao waved his hand. "Besides, if I hadn't used the pole to push through that rapid section, we might be swimming under some waterfall right now."

“Magnetic propulsion output only reached 47% of the theoretical value. What truly avoided the impact was your mechanical judgment.” Nana looked at him. “Your reaction speed at that moment was 21% faster than in daily tests, and your decision-making error rate dropped to its lowest level in history.”

Chen Hao was taken aback for a moment, then laughed: "You even secretly gave me performance ratings?"

"This is objective data analysis, not subjective evaluation."

“But I think… I’ve really changed.” He looked at the water and lowered his voice. “I used to even try to skip running laps in PE class, but now I’m willing to risk my life for a pole vault.”

Nana paused for a few seconds, then a blue light flashed: "Record Update: Chen Hao demonstrated a sustained improvement in adaptability in extreme environments, and it is recommended that he be included in the reference model for subsequent survival training."

"Don't make it so formal." He waved his hand. "I just grew up a little by accident, it's not like I suddenly became a superhero."

"Your current body fat percentage is still 17% higher than the healthy standard."

"Hey! Don't finish him off now!"

"I'm just providing the real data."

"You robot, the more you spend time with you, the more heartbroken you become." Chen Hao sighed, but couldn't help laughing. "But... you're quite reliable."

The current gradually calmed, the river widened, and slivers of light shone through the cracks in the overhead rocks, reflecting on the water's surface as shimmering, flowing silver spots. The raft moved forward with the gentle current, requiring less frequent maneuvering, and even the air seemed to quiet down.

Chen Hao leaned against the wooden beam, legs stretched out, and relaxed completely. He suddenly pointed to a wisp of eerie blue light shimmering in the water: "Look, don't these lights look like the lighting we used when we first turned on the base?"

Nana followed his gaze and said, "Different types of light sources have significantly different light-emitting mechanisms."

“I know it’s different,” he interrupted her, “but I feel the same way—we’re both in the dark, creating our own light.”

Nana didn't correct her.

Chen Hao seemed to pick up where he left off: "Back then, I thought I'd go crazy after three days in this lousy place. But I ended up staying for two months, and I even paddled a raft deeper and deeper underground myself."

“You once said, ‘I’d rather fail a course in the dorm than come to this godforsaken place.’”

“Yes, I did say that.” He nodded. “But now that I think about it, failing a course is fine, I’ve already retaken it. But if I hadn’t come here, I might never have known that I could do something worthwhile.”

"Your operation error rate when collecting samples was 0.6%, which is considered high-precision operation performance."

"Ha, turns out I'm quite observant?" He chuckled self-deprecatingly. "If my mom heard this, she'd definitely think I was delirious from a fever."

"Your mother is not registered in the system."

“Oh, I forgot, you don’t know her yet.” Chen Hao scratched his head. “If she knew that I could now paddle a raft, pick plants, and dodge rocks in the underground river, she would probably take a picture and post it on her WeChat Moments with the caption ‘My chubby boy has finally been useful.’”

"Use of social media platforms is not within the scope of the current task."

"Can't you just daydream with me for a little while?"

“I can record your language patterns and categorize them as ‘non-task-related emotional release behaviors’.”

"...You are truly heartless."

"I'm just giving the truth."

“Alright.” Chen Hao stood up, steadied himself on the edge of the raft, and flexed his wrists. “Next time, I want to go deeper. Maybe there’s an even bigger lake down there, or even… an exit leading to the surface.”

Nana looked up at him, the blue light steady: "Current energy reserves support extending the expedition by 1.8 hours; it is recommended to retain redundancy for the return trip."

"If you don't object, that means you agree!" He laughed even louder, and gently touched the water's surface with his pole, creating a small ripple.

The raft continued downstream, the fluorescent plants on the cave walls fading into the distance, like pages of a memory slowly closing. Chen Hao sat back down, pulled a small notebook from his pocket, and opened a page. On it were a few lines of crooked writing: "Day 1: Found water. Day 2: Almost got crushed by a rock. Day 3: Invented a new way to play with vines binding wood..."

He turned to the last page, which was blank.

Nana glanced at it: "Do you need me to record what happened next?"

"No need." He closed the notebook and stuffed it back into his inner pocket. "Some things feel better when written down by yourself."

"Your handwriting recognition rate is 63%, which is below the system's recognition threshold."

"That's perfect, it's highly confidential."

"You don't have any confidential information that needs to be protected."

“But I have a story.” He patted his chest. “And this story is only half-written.”

The river continued to flow ahead, its surface calm, with only the faint sound of rafts gliding by. Chen Hao squinted, gazing at the faintly glowing bend in the distance.

"Do you think we could come out again after we go back?"

Looking at the navigation map, Nana said, "Based on the current resources, the next exploration window will be in seventeen days."

"Then it's possible." He grinned. "I'll bring an extra pair of shoes; these are almost completely covered in mud."

"The sole of your left shoe is 37% worn down."

"Look, look, here we go again." He lifted his foot and swung it. "This is called an adventure medal, you know?"

"I don't understand metaphors."

"Then do you understand—" He turned his head, about to speak, when suddenly his body swayed and he hurriedly grabbed the edge of the raft.

The raft crashed violently into a rock ridge half-submerged in the water, causing a muffled thud in the storage compartment.